References of "Baron, Frédéric"
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See detailCytotoxic T-lymphocyte-associated protein 4-Ig effectively controls immune activation and inflammatory disease in a novel murine model of leaky severe combined immunodeficiency
Humblet-Baron, Stephanie; Schönefeldt, Susan; Garcia-Perez, Josselyn E et al

in Journal of Allergy and Clinical Immunology (The) (in press)

Background: Severe combined immunodeficiency (SCID) can be caused by loss-of-function mutations in genes involved in the DNA recombination machinery, such as RAG1, RAG2 or DCLRE1C. Defective DNA ... [more ▼]

Background: Severe combined immunodeficiency (SCID) can be caused by loss-of-function mutations in genes involved in the DNA recombination machinery, such as RAG1, RAG2 or DCLRE1C. Defective DNA recombination causes a developmental block in T cells and B cells, resulting in high susceptibility to infections. Hypomorphic mutations in the same genes can also give a partial loss of T cells, in a spectrum including leaky SCID (LS) and Omenn syndrome (OS). These patients not only develop life-threatening infections due to immunodeficiency, but also develop inflammatory/autoimmune conditions due to the presence of autoreactive T cells. Objective: We sought to develop a preclinical model that fully recapitulates the symptoms of LS/OS patients including a model for testing therapeutic intervention. Methods: We generated a novel mutant mouse (Dclre1c leaky) that develops a LS phenotype. Mice were monitored for diseases and immune phenotype and immune function were evaluated using flow cytometry, ELISA and histology. Results: Dclre1c leaky mice present with a complete blockade of B cell differentiation, with a leaky block in T cell differentiation resulting in an oligoclonal TCR repertoire and enhanced cytokine secretion. Dclre1c leaky mice also developed inflammatory symptoms including wasting, dermatitis, colitis, hypereosinophilia and high IgE levels. Development of a preclinical murine model for LS allowed the testing of potential treatment, with administration of CTLA4-Ig reducing disease symptoms and immunological disturbance, resulting in increased survival. Conclusion: These data suggest that CTLA4-Ig should be evaluated as a potential treatment of inflammatory symptoms in LS and OS patients. [less ▲]

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See detailFocus sur les lymphocytes T dans la maladie du greffon contre l'hôte après allogreffe de cellules soucges hématopoïétiques: implications pour de nouvelles stratégies de prévention
Vrancken, L; Delens, Loïc ULg; BEGUIN, Yves ULg et al

in Oncol. Hematol. (in press)

Malgré les stratégies de prévention actuelles, la maladie du greffon contre l’hôte (greffe-versus-hôte, GVH) aiguë (GVHa) reste une complication sévère et fréquente de l’allogreffe de cellules souches ... [more ▼]

Malgré les stratégies de prévention actuelles, la maladie du greffon contre l’hôte (greffe-versus-hôte, GVH) aiguë (GVHa) reste une complication sévère et fréquente de l’allogreffe de cellules souches hématopoïétiques. Bien que la physiopathologie de celle-ci ne reste que partiellement élucidée à ce jour, il est classiquement admis que les lymphocytes T (LT) jouent un rôle important dans son processus biologique. Les progrès récents de l’immunologie des LT dans la GVHa ont permis de diversifier les pistes visant à prévenir la survenue de cette complication post-greffe. Plusieurs approches sont en cours d’exploration dans des essais cliniques avec des résultats encourageant tels que la manipulation ex vivo des LT avant leur transfert chez le patient afin de leur faire exprimer des gènes suicide, l’élimination in vivo des LT proliférant directement après la greffe, l’inhibition de l’activation des LT en interférant avec les voies de signalisation en aval du TCR ou celles induites par les cytokines, l’induction de l’anergie des LT en bloquant les signaux de costimulation, le blocage de l’adressage des LT vers les organes lymphoïdes secondaires et les tissus cibles, la promotion de l’immunotolérance par la perfusion de lymphocytes T régulateurs ou par l’utilisation d’agents favorisant leur différenciation et leurs fonctions in vivo et la modulation de l’expression génique des cellules immunitaires par des modulateurs épigénétiques. Outre la prévention de la GVHa, le défi des nouvelles stratégies consiste également à ne pas compromettre l’effet bénéfique de la greffe contre la tumeur ni la reconstitution des défenses anti-infectieuses. [less ▲]

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See detailAzacytidine prevents experimental xenogeneic graft-versus-host disease without abrogating graft-versus-leukemia effects
Ehx, Grégory ULg; Fransolet, Gilles ULg; De Leval, Laurence et al

in Oncoimmunology (2017)

The demethylating agent 5-azacytidine (AZA) has proven its efficacy as treatment for myelodysplastic syndrome and acute myeloid leukemia. In addition, AZA can demethylate FOXP3 intron 1 (FOXP3i1) leading ... [more ▼]

The demethylating agent 5-azacytidine (AZA) has proven its efficacy as treatment for myelodysplastic syndrome and acute myeloid leukemia. In addition, AZA can demethylate FOXP3 intron 1 (FOXP3i1) leading to the generation of regulatory T cells (Treg). Here, we investigated the impact of AZA on xenogeneic graft-versus-host disease (xGVHD) and graft-versus-leukemia effects in a humanized murine model of transplantation (human PBMCs-infused NSG mice), and described the impact of the drug on human T cells in vivo. We observed that AZA improved both survival and xGVHD scores. Further, AZA significantly decreased human T-cell proliferation as well as IFN-γ and TNF-α serum levels, and reduced the expression of GRANZYME B and PERFORIN 1 by cytotoxic T cells. In addition, AZA significantly increased Treg frequency through hypomethylation of FOXP3i1 as well as increased Treg proliferation. The later was subsequent to higher STAT5 signaling in Treg from AZA-treated mice, which resulted from higher IL-2 secretion by conventional T cells from AZA-treated mice itself secondary to demethylation of the IL-2 gene promoter by AZA. Importantly, Tregs harvested from AZA-treated mice were suppressive and stable over time since they persisted at high frequency in secondary transplant experiments. Finally, graft-versus-leukemia effects (assessed by growth inhibition of THP-1 cells, transfected to express the luciferase gene) were not abrogated by AZA. In summary, our data demonstrate that AZA prevents xGVHD without abrogating graft-versus-leukemia effects. These findings could serve of basis for further studies of GVHD prevention by AZA in acute myeloid leukemia patients offered an allogeneic transplantation. [less ▲]

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See detailXenogeneic graft-versus-host disease : Impact of Th17 cells
Delens, Loïc ULg; SERVAIS, Sophie ULg; Vrancken, Louise ULg et al

Poster (2017, March 27)

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See detailImmunomodulatory effects of rapamycin in xenogeneic Graft versus Host Disease
Ehx, Grégory ULg; Hannon, Muriel ULg; DUBOIS, Sophie ULg et al

in Biology of Blood and Marrow Transplantation (2017, March), 23(3), 365366

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Several studies have suggested that rapamycin (RAPA), an mTOR ... [more ▼]

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Several studies have suggested that rapamycin (RAPA), an mTOR inhibitor with immunosuppressive properties, may reduce GVHD severity and mortality, possibly by promoting regulatory T cells (Tregs). However, few data have been reported about the impact of this drug on overall T cell population. The present work aims at investigating the mechanisms by which RAPA impacts GVHD in a humanized mouse model of GVHD (NSG mice infused with human PBMCs). We observed that RAPA injections significantly reduced xenogeneic GVHD lethality and severity. RAPA dramatically reduced human cells chimerism in RAPA mice and increased CD4+/CD8+ T cells balance due to a lower proliferation of CD8+ T cells. In addition, the frequencies of naive CD4+ and CD8+ T cells were higher and the CD4+ T cells showed a reduced effector phenotype (CD45RO+CD27-). Further, the differentiation of helper T cells (Th1, Th2 and Th17) was significantly decreased in treated mice. Tregs were positively affected as RAPA up-regulated their expression of BCL-2 and KI67 as well as their STAT5 phosphorylation level, leading to higher Treg frequency in treated mice. Altogether these data suggest that RAPA ameliorates GVHD by lowering cytotoxic and effector CD4+ T cells frequency as well as promoting Tregs. [less ▲]

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See detailUNE INJECTION UNIQUE DE CELLULES STROMALES MESENCHYMATEUSES AU JOUR 3 APRES GREFFE HEPATIQUE EST INSUFFISANTE POUR INDUIRE UNE TOLERANCE OPERATIONNELLE
DETRY, Olivier ULg; VANDERMEULEN, Morgan ULg; DELBOUILLE, Marie-Hélène ULg et al

in Transplant International (2017, January), 30(suppl 1), 812

Introduction: Mesenchymal stromal cell (MSC) infusion could be a mean to establish donor-specific immunological tolerance in solid organ recipients. The aim of this phase 2 study was test the hypothesis ... [more ▼]

Introduction: Mesenchymal stromal cell (MSC) infusion could be a mean to establish donor-specific immunological tolerance in solid organ recipients. The aim of this phase 2 study was test the hypothesis of possible induction of operative tolerance by third-party MSC in liver transplant (LT) recipients. Methods: 10 stable and low-risk LT recipients under standard immunosup- pression (Tac-MMF- low dose steroids) received 1.5–3 9 106/kg third-party MSCs on post-operative day 3 ` 2. By protocol, progressive weaning of immunosuppression was attempted in patients who did not develop rejection and had normal graft function and month-6 graft biopsy. Tacrolimus was progressively tapered from day 180 to be discontinued by day 270. After day- 270 graft biopsy, MMF was progressively tapered and definitely discontinued by day 365 in the absence of rejection. Results: One patient from the MSC group was excluded from immunosup- pression withdrawal attempt due to HCC recurrence, and the 9 others met the necessary criteria. In one patient, tacrolimus and MMF withdrawal was performed without rejection. In two patients, MMF monotherapy was achieved at month 9, but graft rejection occurred during MMF withdrawal and was successfully treated by tacrolimus reintroduction. In 6 patients, the transam- inases significantly increased during tacrolimus withdrawal. In these cases, withdrawal was cancelled and liver tests normalised after increase of the tacrolimus dose. No graft was lost due to the withdrawal attempt. Conclusion: A single post transplant MSC injection is not sufficient to induce operative tolerance after LT. [less ▲]

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See detailThe role of mesenchymal stem cells in the treatment of ulcerative colitis and Crohn's disease
GREGOIRE, Céline ULg; Louis, Edouard ULg; BRIQUET, Alexandra ULg et al

in The Biology and Therapeutic Application of Mesenchymal Cells (2017)

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See detailInfusion of mesenchymal stromal cells after deceased liver transplantation: A phase I-II, open-label, clinical study.
DETRY, Olivier ULg; VANDERMEULEN, Morgan ULg; DELBOUILLE, Marie-Hélène ULg et al

in Journal of Hepatology (2017)

BACKGROUND & AIM: Mesenchymal stromal cell (MSC) infusion could be a mean to establish tolerance in solid organ recipients. The aim of this prospective, controlled, phase-1 study was to evaluate the ... [more ▼]

BACKGROUND & AIM: Mesenchymal stromal cell (MSC) infusion could be a mean to establish tolerance in solid organ recipients. The aim of this prospective, controlled, phase-1 study was to evaluate the feasibility, safety and tolerability of a single infusion of MSCs in liver transplant recipients. METHODS: Ten liver transplant recipients under standard immunosuppression received 1.5-3x106/kg third-party unrelated MSCs on post-operative day 3+/-2, and were prospectively compared to a control group of 10 liver transplant recipients. As primary end-points, MSC infusional toxicity was evaluated, and infectious and cancerous complications were prospectively recorded until month 12 in both groups. As secondary end-points, rejection rate, month-6 graft biopsies, and peripheral blood lymphocyte phenotyping were compared. Progressive immunosuppression weaning was attempted from month 6 to 12 in MSC recipients. RESULTS: No variation in vital parameters or cytokine release syndrome could be detected during and after MSC infusion. No patient developed impairment of organ functions (including liver graft function) following MSC infusion. No increased rate of opportunistic infection or de novo cancer was detected. As secondary end-points, there was no difference in overall rates of rejection or graft survival. Month-6 biopsies did not demonstrate a difference between groups in the evaluation of rejection according to the Banff criteria, in the fibrosis score or in immunohistochemistry (including Tregs). No difference in peripheral blood lymphocyte typing could be detected. The immunosuppression weaning in MSC recipients was not successful. CONCLUSIONS: No side effect of MSC infusion at day 3 after liver transplant could be detected, but this infusion did not promote tolerance. This study opens the way for further MSC or Treg-based trials in liver transplant recipients. LAY SUMMARY: Therapy with mesenchymal stromal cells (MSCs) has been proposed as a mean to improve results of solid organ transplantation. One of the potential MSC role could be to induce tolerance after liver transplantation, i.e. allowing the cessation of several medications with severe side effects. This study is the first-in-man use of MSC therapy in 10 liver transplant recipients. This study did not show toxicity after a single MSC infusion but it was not sufficient to allow withdrawal of immunosuppression. [less ▲]

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See detailMultiple myeloma bone disease: from mechanisms to next generation therapy
Heusschen, Roy ULg; Muller, Joséphine ULg; WITHOFS, Nadia ULg et al

in Belgian Journal of Hematology (2017)

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See detailMesenchymal stromal cell therapy for inflmmatory bowel diseases
GREGOIRE, Céline ULg; LECHANTEUR, Chantal ULg; BRIQUET, Alexandra ULg et al

in Alimentary Pharmacology & Therapeutics (2017), 45

Background Inflammatory bowel diseases (IBD) are chronic relapsing diseases in which pro-inflammatory immune cells and cytokines induce intestinal tissue damage and disability. Mesenchymal stromal cells ... [more ▼]

Background Inflammatory bowel diseases (IBD) are chronic relapsing diseases in which pro-inflammatory immune cells and cytokines induce intestinal tissue damage and disability. Mesenchymal stromal cells (MSCs) exert powerful immunomodulatory effects and stimulate tissue repair. Aim To review the current data on mesenchymal stromal cell therapy in IBD. Method We searched PubMed and ‘ClinicalTrials.gov’ databases using the terms ‘mesenchymal stromal cells’, ‘mesenchymal stem cell transplantation’, ‘inflammatory bowel diseases’, ‘Crohn disease’ and ‘colitis, ulcerative’. Additional publications were identified from individual article reference lists. Results MSCs include inhibition of Th1/Th17 lymphocytes and recruitment of regulatory T lymphocytes, induction of antigen-presenting cells into a regulatorylike profile, and stimulation of epithelial cell differentiation and proliferation. More than 200 patients with refractory fistulas have been treated with local injections of MSCs, resulting in complete response in more than half, and in overall response in approximately two thirds of patients. In refractory luminal Crohn’s disease, 49 cases of systemic MSC infusions have been reported, while trials with autologous MSCs resulted in mitigated responses, studies using allogeneic MSCs were promising, with around 60% of patients experiencing a response and around 40% achieving clinical remission. Conclusions Mesenchymal stromal cells might represent a promising therapy for IBD, especially for Crohn’s disease. There remain many unsolved questions concerning the optimal origin and source of mesenchymal stromal cells, dosage and modalities of administration. Moreover, mesenchymal stromal cells still need to prove their effectiveness compared with conventional treatments in randomised controlled trials. [less ▲]

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See detailAnti-thymocyte globulin as graft-versus-host disease prevention in the setting of allogeneic peripheral blood stem cell transplantation: a review from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.
Baron, Frédéric ULg; Mohty, Mohamad; Blaise, Didier et al

in Haematologica (2017)

Allogeneic hematopoietic stem cell transplantation is increasingly used as treatment for patients with life threatening blood diseases. Their curative potential is largely based on immune-mediated graft ... [more ▼]

Allogeneic hematopoietic stem cell transplantation is increasingly used as treatment for patients with life threatening blood diseases. Their curative potential is largely based on immune-mediated graft-versus-leukemia effects caused by donor T cells contained in the graft. Unfortunately, donor T cells are also the cause of graft-versus-host disease. The vast majority of HLA-matched allogeneic hematopoietic stem cell transplantations are nowadays carried out with peripheral blood stem cells (PBSC) as stem cell source. In comparison with bone marrows, PBSC contain more hematopoietic stem/progenitor cells but also one log more T cells. Consequently, the use of PBSC instead of bone marrow has been associated with faster hematological recovery and a lower risk of relapse in patients with advanced disease, but also with a higher incidence of chronic graft-versus-host disease. These observations have been the basis for several studies aimed at assessing the impact of immunoregulation with anti-thymocyte globulin (ATG) on transplantation outcomes in patients given HLA-matched PBSC from related or unrelated donors. After a brief introduction on ATG, this article reviews recent studies assessing the impact ATG on transplantation outcomes in patients given PBSC from HLA-matched related or unrelated donors as well as in recipients of grafts from HLA-haploidentical donors. [less ▲]

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See detailA surprising and dramatic neuroendocrine-immune phenotype of mice deficient in Growth Hormone-Releasing Hormone (GHRH)
Farhat, Khalil; Bodart, Gwennaelle; Martens, Henri ULg et al

in Neuroimmunomodulation (2017)

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See detailNovel strategies for improving hematopoietic reconstruction after allogeneic hematopoietic stem cell transplantation or intensive chemotherapy.
Baron, Frédéric ULg; Nagler, Arnon

in Expert Opinion on Biological Therapy (2017)

INTRODUCTION: High-dose conditioning regimens for allogeneic hematopoietic cell transplantation (allo-HCT) as well as intensive poly-chemotherapy for acute myeloid leukemia (AML) induce prolonged periods ... [more ▼]

INTRODUCTION: High-dose conditioning regimens for allogeneic hematopoietic cell transplantation (allo-HCT) as well as intensive poly-chemotherapy for acute myeloid leukemia (AML) induce prolonged periods of neutropenia. The duration of the neutropenia is particularly long following umbilical cord blood transplantation (UCBT). Areas covered: After briefly reviewing the impact of hematopoietic growth factors administration to hasten hematologic reconstitution after allo-HCT or intensive AML chemotherapy, this article summarizes recent approaches that have been investigated to prompt hematologic reconstruction after UCBT or intensive AML chemotherapy. Expert opinion: In the allo-HCT setting, administration of G-CSF or GM-CSF shortened the duration of the neutropenia but failed to decrease infection-related mortality or to improve survival. Novel approaches to hasten hematological reconstruction after UCBT such as double UCBT with expansion of one of the 2 UCB units with Notch ligand, mesenchymal stromal cells, nicotinamide, or StemRegenin 1, co-transplanting a single UCB unit with HLA-haploidentical CD34+ cells, or increasing UCB HSC homing to marrow niches via direct intra bone UCB administration, pulse treatment with dmPGE2 or enforced fucosylation are promising and deserve further investigations in prospective phase III studies. In the AML setting, G-CSF or GM-CSF administration after intensive chemotherapy decreased the duration of the neutropenia without improving survival. [less ▲]

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See detailOutcomes of UCB transplantation are comparable in FLT3+ AML: Results of CIBMTR, eurocord and EBMT collaborative analysis.
Ustun, C.; Giannotti, F.; Zhang, M.-J. et al

in Leukemia : Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K (2017)

Allogeneic hematopoietic cell transplantation (HCT) from siblings or unrelated donors (URD) during complete remission (CR) may improve leukemia-free survival (LFS) in FLT3+ acute myeloid leukemia (AML ... [more ▼]

Allogeneic hematopoietic cell transplantation (HCT) from siblings or unrelated donors (URD) during complete remission (CR) may improve leukemia-free survival (LFS) in FLT3+ acute myeloid leukemia (AML) that has poor prognosis due to high relapse rates. Umbilical cord blood (UCB) HCT outcomes are largely unknown in this population. We found that compared with sibling HCT, relapse risks were similar after UCB (n=126), (HR 0.86, P=0.54) and URD (n=91) (HR 0.81, P=0.43). UCB HCT was associated with statistically higher non-relapse mortality compared with sibling HCT (HR 2.32, P=0.02), but not vs URD (HR 1.72, P=0.07). All three cohorts had statistically not significant 3-year LFS: 39% (95% CI 30-47) after UCB, 43% (95% CI 30-54) after sibling, and 50% (95% CI 40-60) after URD. Chronic GVHD rates were significantly lower after UCB compared with either sibling (HR 0.59, P=0.03) or URD (HR 0.49, P=0.001). Adverse factors for LFS included high leukocyte count at diagnosis and HCT during CR2. UCB is a suitable option for adults with FLT3+AML in the absence of an HLA-matched sibling and its immediate availability may be particularly important for FLT3+ AML where early relapse is common thus allowing HCT in CR1 when outcomes are best.Leukemia accepted article preview online, 25 January 2017. doi:10.1038/leu.2017.42. [less ▲]

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See detailLimited Impact of Imatinib in a Murine Model of Sclerodermatouc Chronic Graft-versus-Host Disease
Belle, Ludovic ULg; Fransolet, Gilles ULg; Somja, Joan ULg et al

in PLoS ONE (2016), 11

Background Sclerodermatous chronic Graft-versus-Host Disease (scl-cGVHD) is one of the most severe form of cGVHD. The Platelet-derived Grotwth Factor (PDGF) and the Transforming Growth Factor-β (TGF-β ... [more ▼]

Background Sclerodermatous chronic Graft-versus-Host Disease (scl-cGVHD) is one of the most severe form of cGVHD. The Platelet-derived Grotwth Factor (PDGF) and the Transforming Growth Factor-β (TGF-β) play a significant role in the fibrosing process occurring in scl-cGVHD. This prompted us to assess the impact of the PDGF-r and c-Abl tyrosine kinase inhibitor imatinib on scl-cGVHD. Methods To assess the impact of imatinib on T cell subset proliferation in vivo, Balb/cJ recipient mice were lethally (7 Gy) irradiated and then injected with 10x106 bone marrow cells from B10.D2 mice on day 0. Fourteen days later, 70x106 carboxyfluorescein succinimidyl ester (CFSE)-labeled splenocytes from B10.D2 mice were infused and imatinib or sterile water was administered for 5 days. To induce severe scl-cGVHD, Balb/cJ mice were injected i.v. with 10.106 bone marrow cells and 70.106 splenocytes from B10.D2 donor mice after 7 Gy irradiation. Mice were then given sterile water or imatinib from day +7 after transplantation to the end of the experiment (day +52). Results Imatinib decreased the proliferation of total T cells (P = 0.02), CD8+ T cells (P = 0.01), and of regulatory T cells (Tregs) (P = 0.02) in the spleen. In the severe scl-cGVHD model, imatinib-treated mice had significantly lower levels of PDGF-r phosphorylation than control mice on day 29 after transplantation (P = 0.008). However, scl-cGVHD scores were similar between vehicle- and imatinib-treated mice during the whole experiment, while there was a suggestion for less weight loss in imatinib-treated mice that reached statistical significance at day +52 following transplantation (P = 0.02). [less ▲]

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