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International audience; Melanoma prognosis is dictated by tumor-infiltrating lymphocytes, the migratory and functional behavior of which is guided by chemokine or cytokine gradients. Here, we retrospectively analyzed the expression patterns of 9 homing receptors (CCR/CXCR) in naive and memory CD4+ and CD8+ T lymphocytes in 57 patients with metastatic melanoma (MMel) with various sites of metastases to evaluate whether T cell CCR/CXCR expression correlates with intratumoral accumulation, metastatic progression, and/or overall survival (OS). Homing receptor expression on lymphocytes strongly correlated with MMel dissemination. Loss of CCR6 or CXCR3, but not cutaneous lymphocyte antigen (CLA), on circulating T cell subsets was associated with skin or lymph node metastases, loss of CXCR4, CXCR5, and CCR9 corresponded with lung involvement, and a rise in CCR10 or CD103 was associated with widespread dissemination. High frequencies of CD8+CCR9+ naive T cells correlated with prolonged OS, while neutralizing the CCR9/CCL25 axis in mice stimulated tumor progression. The expansion of CLA-expressing effector memory CD8+ T cells in response to a single administration of CTLA4 blockade predicted disease control at 3 months in 47 patients with MMel. Thus, specific CCR/CXCR expression patterns on circulating T lymphocytes may guide potential diagnostic and therapeutic approaches.

10032 The treatment of dermatofibrosarcoma protuberans (DFSP) relies on a wide local excision with frequent need of reconstructive surgery. A (17,22)translocation with Co1A1-PDGF fusion is present in > 90 % of the cases. Some patient's observations and a report on 9 patients suggest that Imatinib mesylate (IM), targeting PDGFRβ, has a clinical interest in DFSP. The primary aim of this phase II multicentric study was to define the percentage of clinical responders (RECIST) to a preoperative 2 months 600mg IM daily before wide local excision. The secondary goals were to determine tolerance, imaging (ultrasound and MRI), pathological responses and to analyse PDGFRβ phosphorylation status and tumour cell apoptosis in sequential tissues specimen. A flexible design with interim analysis after recruitment of 6 patients was used. 18 to 28 patients had to be enrolled to detect a 30% clinical response rate (relative decrease of tumor of at least 30%) with power 80%, using a one-sided test against 5%, at the 2.5% one-sided level. The interim analysis yielded a clinical response in 3 of 6 patients without severe adverse event. An independent committee advised to continue the trial to obtain a total number of at least 24 patients, in order to reduce the confidence interval of response rate. Twenty-five adults suffering from primary or recurrent DFSP have been included from July 2004 to May 2006, 13F and 12 M, median age 42.4 years [range 23.0–72.5]. Tumour characteristics were as follows: primary (n=20), recurrence (n=5) involving trunk(n=14), head or neck (n=3), limbs (n=6), other n=2; median size was 4.5cm [range 2.4–16]. Translocation t(17;22) was detected in 12 of 12 informative tumours following caryotype or FISH analysis. A clinical response was achieved in 9 (36%) patients(95%CI 18.9–57.5). The median relative decrease of tumor was of 20.0% [range -12.5;100]. Apart from expected grade 1 or 2 side effects, we observed 1 grade 3 neutropenia, 1 grade 3 maculopapular rash and 1 grade 4 transient transaminitis. Imatinib has been recently approved for the treatment of unresectable or metastatic dermatofibrosarcoma. Our results should prompt us to analyse the clinical benefit of a longer duration neoadjuvant treatment for patients with DFSPin order to reduce surgical margins [Table: see text]

e20113 Background: Recent advances in treatment of metastatic melanoma highlight how important collecting and building databases are, for a better health care management (overall survival, safety, ...

9550 Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue sarcoma of intermediate malignant potential. Treatment relies on a wide local excision with negative margin with frequent need of reconstructive surgery. A translocation between chromosomes 17 and 22 that places PDGFB under the control of the collagen 1A1 promoter is present in > 90% of the cases leading to an up regulation of PDGFB expression and activation of the tyrosinase kinase PDGFRβ. Anecdotal reports and a report on 8 patients suggest that Imatinib mesylate (IM) has a clinical interest in DFSP. The primary aim of this phase II multicentric study is to define the percentage of clinical responders (RECIST) to a preoperative 2 months 600mg IM daily before wide local excision. The secondary goals are to determine tolerance, imaging (ultrasound and MRI), pathological responses and to analyse PDGFRβ phosphorylation status and tumour cell apoptosis in sequential tissues specimen. Fifteen adults suffering from primary or recurrent DFSP have been included since July 2004. All tumors had a diameter ≥2cm. A flexible design with interim analysis after recruitment of 6 patients was used. 18 to 28 patients had to be enrolled to detect a 30% response rate with power 80%, using a one-sided test against 5%, at the 2.5% level. Three men and 3 women, median age 48.4 years [23; 72.5] have been evaluated. Tumour characteristics are as follows : primary (n=4), recurrence (n=2) all involved trunk, median size 5.75cm [2.5–12]. Tolerance was good apart from grade 1 facial oedema (n=6) grade 2 maculopapular rash (n=1), grade 1 asthenia (n=1), grade 1 pyrosis (n=2). Translocation t(17;22) was detected in all tumours. A partial response was achieved in 3 of 6 patients. The median relative decrease of tumor in the PR and non responder patients was of 21.9% [−3.3; 72.0]. Histological analysis revealed a global decrease of cellularity often accompanied with a CD34 loss of expression, a fibrosis and mild peripheral lymphoid infiltrates. No evidence of apoptosis on tissue specimen after surgery was observed using TUNEL. These encouraging interim results weresubmitted to an independent committee who allowed to continue the trial and to include a total of 24 patients in order to reduce the confidence interval of response rate. [Table: see text]

9093 Background: Vemurafenib is the first approved by the FDA BRAF V600 inhibitor for the treatment of metastatic melanoma. Many cutaneous side-effects such as squamous cell carcinoma, xerosis, photosensitivity are observed. We first reported the occurrence of second primary melanomas (SPM) under BRAF inhibition. These SPM were shown to be wild-type for BRAF. The exact occurrence of these changes is still unknown. We wanted then to explore prospectively the impact of vemurafenib on cutaneous pigmented lesions using sequential digital dermoscopy. Methods: We registered prospectively following inform consent the pigmented lesions of patients under vemurafenib. We examined the total body surface and captured from 9 to 134 pigmented lesions on 24 patients. Each single lesion was followed monthly from vemurafenib initiation to vemurafenib disruption due to disease progression. Dermoscopic modifications of the melanocytic lesions including external diameter, dermoscopical pattern, pigmentation, network thickness, dots distribution and keratosis appearance were analyzed. Results: The median duration of dermoscopic follow up was 6,9 months ( range from 2 to 16 months), 1098 pigmented lesions were included. At least one modification occurred in 56% of the lesions. Most frequent modifications were the occurrence of dark globules (56%), change in the pigmentation coloration (47%), variations in network thickness (32%), increase of the external size (20,1%), onset of black areas (14%), onset of keratosis (4,4%). Up to 5,3% of lesions spontaneously disappeared; 21 excisions were performed due to significant dermoscopic changes and revealed 10 early melanomas in 5/24 patients (20,8%). The 11 remaining lesions were benign. Conclusions: More than fifty percent of the patients under vemurafenib will experiment significant modifications on their pigmented lesions. In our experience 10/21 removed lesions were early melanomas that could not be otherwise diagnosed using naked-eyes examinations only. Digital dermoscopy is one of the tool that can be use to discriminate earlier the modifications. Such careful monitoring will improved the safety when evaluating BRAF inhibitors in adjuvant setting.

e20062 Background: A recent French national phase II clinical trial (NCT01168050) evaluating nilotinib in KIT mutated advanced melanoma showed an overall response rate of 20% (Lebbe et al, ASCO 201...

Introduction: Cutaneous T- cell lymphoma (CTCL) is a rare form of non-Hodgkin lymphoma. Patients with CTCL suffer reduced quality of life from intractable itching and recurrent infections. Advanced stages have a poor prognosis. Mogamulizumab (Moga) is a monoclonal antibody directed against chemokine receptor 4 (CCR4), which is overexpressed on malignant T-cells. In a Phase I-II study in CTCL, Moga demonstrated a tolerable safety profile with a 37% overall response rate (ORR). Based on these results, MAVORIC [NCT01728805], an open-label, multinational, randomized, Phase III study, was initiated to compare Moga to vorinostat (Vor) in previously treated CTCL. This study is the largest randomized trial and the first pivotal trial to use progression-free survival (PFS) as a primary endpoint in CTCL. Methods: Adult patients with histologically confirmed mycosis fungoides (MF) or Sézary syndrome (SS) who had failed ≥1 systemic therapy were enrolled, stratified by disease type (MF or SS) and stage (IB/II or III/IV), and randomized 1:1 to Moga 1.0 mg/kg (weekly for the first 4-week cycle and then every 2 weeks) or Vor (400 mg daily). Patients randomized to Vor could crossover to Moga upon progression or intolerable toxicity. The primary endpoint was investigator-assessed PFS in the randomized population using the global composite response (based on skin, blood, nodes and viscera) according to the ISCL/EORTC consensus guidelines. Sample size was calculated to provide 90% power to detect a 50% improvement in PFS. Key secondary endpoints included ORR, duration of response (DOR) and quality of life (QoL). Results: A total of 372 patients were randomized (Intent-to-Treat population) and had the following characteristics (Moga vs Vor): median age 63.5 yrs (25-101) vs 65.0 yrs (25-89); ECOG-PS 0-1, 184 (99%) vs 186 (100%); ECOG-PS 2, 2 (1%) vs 0; stage IB/IIA, 36 (19.4%) vs 49 (26.3%); stage IIB, 32 (17.2%) vs 23 (12.4%); stage III/IV, 118 (63.4%) vs 114 (61.3%); MF, 105 (56.5%) vs 99 (53.2%); SS, 81 (43.5%) vs 87 (46.8%). The median number of prior systemic treatments for both the Moga and Vor arms was 3. According to investigator assessment, treatment with Moga resulted in a significant improvement in PFS compared to Vor (HR 0.53 [95% CI: 0.41, 0.69], p20%) that were more frequent (>15% difference) in the Moga vs Vor arm included infusion-related reactions (33.2% vs 0.5%, respectively) and skin eruptions due to drug (23.9% vs 0.5%, respectively). The majority of TEAEs with Moga were mild to moderate in severity (grade I/II, 54.9%; grade III/IV/V, 42.4%). Common TEAEs reported more often with Vor vs Moga included diarrhea (61.8% vs 23.4%), nausea (42.5% vs 15.2%), thrombocytopenia (30.6% vs 11.4%), dysgeusia (29.0% vs 3.3%), and increased blood creatinine (28.0% vs 3.3%). Conclusions: In this first report of a randomized Phase III study evaluating PFS as primary endpoint in CTCL, Moga, a novel CCR4-targeting antibody therapy, demonstrated significantly superior PFS, ORR, and QoL compared to Vor in patients with previously treated CTCL. The safety profile was consistent with previous reports. This study supports Moga as a valuable new therapeutic option in patients with CTCL. Disclosures Kim: Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Research Funding; Soligenix: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Portola: Consultancy, Research Funding; Neumedicine: Research Funding; miRagen: Research Funding; Merck: Research Funding; Medivir: Membership on an entity's Board of Directors or advisory committees; Kyowa-Kirin-Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate Pharma: Consultancy, Research Funding; Horizon Pharma: Consultancy, Research Funding; Forty Seven Inc: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tetralogic: Research Funding; Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees. Bagot: Innate Pharma: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Actelion: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Kyowa: Membership on an entity's Board of Directors or advisory committees. Horwitz: Kyowa-Hakka-Kirin: Consultancy, Research Funding; Mundipharma: Consultancy; ADCT Therapeutics: Research Funding; Forty-Seven: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; HUYA: Consultancy; Millenium/Takeda: Consultancy, Research Funding; BMS: Consultancy; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Aileron Therapeutics: Research Funding. Whittaker: Celgene: Honoraria; Galderma: Research Funding. Vermeer: Innate Pharma safety board for IPH4102-101: Membership on an entity's Board of Directors or advisory committees. Zinzani: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; J&J: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees. Sokol: Spectrum Pharmaceuticals: Consultancy, Research Funding; Spectrum Pharmaceuticals: Consultancy. Kim: Kyowa Kirin Pharmaceutical Development, Inc.: Other: Clinical trials investigator; Solgenix: Other: Clinical trials investigator; Actelion: Consultancy; Cutaneous Lymphoma Foundation: Membership on an entity's Board of Directors or advisory committees; US Cutaneous Lymphoma Consortium: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy. Ortiz-Romero: ACTELION: Consultancy; 4SC: Consultancy; Innate Pharma: Consultancy; Takeda: Consultancy; MEDA: Research Funding. Eradat: Abbvie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Genentech: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding; Novartis: Research Funding; Celgene: Research Funding; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding. Scarisbrick: 4SC: Consultancy; Takeda: Consultancy; Mallinckrodt: Consultancy; Innate Pharma: Consultancy; Actelion: Consultancy. Elmets: NCI: Research Funding; Veterans Administration: Research Funding; California Wine Grape Assn: Research Funding; Solegenix: Research Funding; Idera: Research Funding; Elorac: Research Funding; Ferndale Labs: Consultancy, Research Funding; Astellas Pharma: Research Funding. Dalle: Kyowa Hakko Kirin Pharmaceutical: Research Funding. Fisher: Celgene: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees. Halwani: Amgen: Research Funding; Pharmacyclics: Research Funding; Takeda: Research Funding; Genetech Inc.: Research Funding; Roche/Genentech Inc.: Research Funding; Seattle Genetics: Research Funding; Bristol Myers Squib: Research Funding; Kyowa Hikko Kirin: Research Funding; AbbVie: Research Funding; Immune Design: Research Funding; Miragen: Research Funding. Poligone: Actelion Pharmaceutical: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy; Kyowa Hakko Kirin: Research Funding; Soligenix: Research Funding. Khot: Celgene: Consultancy; Janssen: Consultancy; Amgen: Other: Travel Grant. Moskowitz: Incyte: Research Funding; Takeda: Honoraria; Bristol Myers-Squibb: Consultancy, Research Funding; ADC Therapeutics: Research Funding; Seattle Genetics: Honoraria, Research Funding. Dwyer: Kyowa Kirin Pharmaceutical Development, Inc.: Employment. Moriya: Kyowa Kirin Pharmaceutical Development, Inc.: Employment. Humphrey: KYOWA KYRIN PHARMACEUTICAL DEVELOPMENT: Employment. Hudgens: Clinical Outcomes Solutions: Consultancy, Research Funding. Grebennik: Kyowa Kirin Pharmaceutical Development, Inc.: Employment. Tobinai: AbbVie: Research Funding; Chugai: Honoraria, Research Funding; Kyowa Hakko Kirin: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Zenyaku Kogyo: Honoraria; GlaxoSmithKline: Research Funding; Takeda: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Servier: Research Funding; Janssen: Honoraria, Research Funding; HUYA Bioscience: Honoraria; Daiichi Sankyo Co., Ltd: Consultancy, Honoraria; Mundipharma: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding. Duvic: MDACC: Other: Safety Oversight Committee, Research Funding.

A small-molecule inhibitor of the MAP3 Kinase TPL2 improves nutrient-induced bêta-cell dysfunction and deathIntroduction : Evidences suggest that nutrient-induced metabolic stresses such as chronic hyperglycemia provide a link between type 2 diabetes and bêta-cell dysfunction and death. If The MAP3 kinase 8, Tumor progression locus 2 (TPL2), plays an important role in bêta-cell death after cytokine exposure, its involvement in bêta-cell dysfunction and death induced by chronic hyperglycemia is unknown.Methods : Insulin secretion is measured by HTRF. Protein expressions (TPL2, cleaved caspase 3 and JNK1 / 2 (death markers), are assessed by Western blotting. Icer mRNA expression is measured by RT-qPCR.Results : We found TPL2 is overexpressed in islets of diabetic GK rats and db/db mice. Chronic hyperglycemia increases TPL2 expression in bêta-cells and human islets. Treatment of db/db mice with a small molecule inhibitor of TPL2 results in a reduction of diabetes progression with decreased fasting hyperglycemia and hyperinsulinemia, improved glucose tolerance, without affecting insulin sensitivity. Inhibition of TPL2 improves the detrimental effects of hyperglycemia on glucose-induced insulin secretion, reduces apoptosis of bêta-cells, and prevents the mRNA upregulation of Icer, a transcriptional repressor of insulin and key exocytotic proteins genes, and c-Jun N-terminal kinases 1/2 (JNK1/2) activation. Combination of a GLP-1 receptor agonist (GLP-1RA, exendin-4) with the TPL2 inhibitor totally prevented the apoptosis of bêta-cells induced by hyperglycemia.Conclusion : Our results identify TPL2 inhibition, alone or in combination with a GLP-1RA, as potential new therapeutic avenues to prevent bêta-cell dysfunction and apoptosis and to slow down T2D development., Une petite molécule inhibitrice de la MAP3 kinase TPL2 améliore la dysfonction et la mort des cellules bêta induite par des nutriments.Introduction : Les preuves suggèrent que les stress métaboliques induits par les nutriments, tel que l'hyperglycémie chronique, établissent un lien entre le diabète de type 2 et le dysfonctionnement et la mort des cellules bêta. Si la MAP3 kinase 8, Tumor progression locus 2 (TPL2), joue un rôle important dans la mort des cellules bêta; après une exposition aux cytokines, son implication dans la dysfonction et la mort induite par hyperglycémie chronique est inconnue.Méthode : La sécrétion d’insuline est mesurée par HTRF. Les expressions protéiques (TPL2, caspase 3 clivée et JNK1/2 (marqueurs de mort), sont évaluées par Western Blotting. L’expression d’ARNm d’Icer, est mesurée par RT-qPCR.Résultats : Nous avons montré que TPL2 est surexprimée dans les îlots de rats GK et de souris db/db. L’hyperglycémie chronique augmente l’expression de TPL2 dans les cellules bêta; et les îlots humains. Le traitement des souris db/db avec une petite molécule inhibitrice de TPL2 entraîne une réduction de la progression du diabète avec une diminution de l'hyperglycémie et de l'hyperinsulinémie à jeun, une meilleure tolérance au glucose, sans affecter la sensibilité à l'insuline. L'inhibition de TPL2 améliore les effets néfastes de l’hyperglycémie sur la sécrétion d’insuline induite par le glucose, réduit l’apoptose des cellules bêta, et empêche la régulation positive de l’ARNm d’Icer, un répresseur transcriptionnel de l'insuline et des gènes clés des protéines d’exocytose, et de l’activation des kinases c-Jun N-terminales 1/2 (JNK1/2). L'association d'un agoniste du récepteur du GLP-1 (GLP-1RA, exendine-4) avec l'inhibiteur de TPL2 a totalement empêché l'apoptose induite par l'hyperglycémie.Conclusion : Nos résultats identifient l’inhibition de TPL2, seule ou en association avec un GLP-1RA, comme une nouvelle stratégie thérapeutique potentielle prometteuse pour prévenir le dysfonctionnement et l’apoptose des cellules bêta et pour ralentir le développement du DT2.

Introduction : The efficacy of islet transplantation is well established. However, the procedure still needs improvements in the quality of grafted islets, often weakened by the loss of their surrounding tissue during the isolation process. In this respect, mesenchymal stromal cells (MSC) represent an interesting tool as they have immunomodulatory and anti-inflammatory properties and are known to secrete proteins involved in creating a favorable microenvironment. This work aims to investigate the effect of human pancreatic stromal cells on human β-cells.Methods : We characterized the mesenchymal profile of cells, previously immortalized in our lab from human islets of Langerhans adherent cells, hereafter named hISC (human islet-derived stromal cells). We seeded human β-cells (EndoC-βH1 cell line or primary β-cells) on hISC-conditioned medium (hISC-CM) used as coating of Petri dishes. We assessed spreading, survival, proliferation and glucose-induced insulin secretion of β-cells cultured on hISC-CM as compared to poly-L-lysine coating.Results : Phenotypic and transcriptomic profiles of hISC are close to bone-marrow MSC. The hISC have an immunomodulation capacity. They express and secrete extracellular matrix proteins known to be present around and within human islet such as types I, IV and VI collagens, laminin and fibronectin. EndoC-βH1 seeded on hISC-CM adhere and spread on cell culture surface. We show that hISC-CM has positive effects on EndocC-βH1 proliferation, survival and glucose-induced insulin secretion, as compared to poly-L-lysine. From mechanistic point of view, hISC-CM induces FAK (focal adhesion kinase) and ERK (extracellular signal-regulated kinases) phosphorylations. The β1-integrin subunit is involved in both adhesion and increased insulin secretion of β cells induced through hISC-CM.Conclusion : Our work demonstrates a promising interest of hISC as support cells for human β-cells by scaffolding factors secretion. It opens new perspectives for conditioning human β-cells in a more physiological microenvironment to preserve their functional quality before and after transplantation., Introduction : L’efficacité de la greffe d’îlots n’est plus à démontrer mais elle reste l’objet de recherches pour améliorer la qualité et la survie des îlots greffés souvent fragilisés par la destruction enzymatique de leur microenvironnement lors de la procédure d’isolement. Dans ce contexte, les cellules stromales mésenchymateuses (CSM) d’origine pancréatique représentent un outil intéressant par leurs propriétés d’immunomodulation et par leur capacité de sécrétion de facteurs du microenvironnement. L’objectif de ce travail est d’évaluer l’effet des cellules stromales pancréatiques humaines sur les cellules β humaines.Méthodes : Des îlots humains purifiés ont été maintenus en culture pendant plusieurs jours. Les cellules adhérentes se formant en périphérie de l’îlot ont été sélectionnées et immortalisées. Ces nouvelles cellules « human islet-derived stromal cells » (hISC) ont ensuite été caractérisées pour déterminer leur profil mésenchymateux Nous avons ensemencé des cellules β humaines (lignée EndoC-βH1 ou cellules primaires) sur du milieu conditionné de hISC (hISC-CM) utilisé comme support de culture. L’adhérence, la survie, la prolifération, l’insulinosécrétion des cellules β cultivées sur le hISC-CM ont été mesurées et comparées à un support contrôle : la poly-L-lysine.Résultats : Les hISC présentent un profil phénotypique et transcriptomique très proche des CSM issues de la moelle osseuse. D’un point de vue fonctionnel, les hISC présentent une capacité d’immunomodulation. Elles expriment et sécrètent des protéines matricielles connues pour être présentes autour et à l’intérieur des îlots humains tels que les collagènes de type I, IV et VI, la laminine et la fibronectine. Au contact du hISC-CM les cellules EndoC-βH sur adhèrent st s’étalent. Le hISC-CM augmente l’expression du marqueur de prolifération PCNA et améliore la survie et la fonction des cellules EndoC-βH1. D’un point de vue mécanistique, l’interaction cellules β/hISC-CM active la phosphorylation de FAK (focal adhesion kinase) et ERK (extracellular signal-regulated kinases). A l’interface de cette interaction, la sous-unité β1 de l’intégrine est impliquée dans les effets observés du hISC-CM sur l’adhérence et la fonction des cellules β.Conclusion : Nos travaux démontrent l’intérêt prometteur des hISC en tant que cellules de soutien des cellules β humaines par la sécrétion de protéines matricielles pancréatiques. Ces résultats ouvrent de nouvelles perspectives pour le maintien des îlots en culture et leur conditionnement dans un microenvironnement plus physiologique permettant ainsi de préserver leur qualité fonctionnelle lors de la greffe.

Pancreatic beta cells synthesize and secrete insulin, the only hypoglycemic hormone in the body. These cells play a central role in the onset of diabetes. To protect the functional beta-cell mass is essential. The GLP-1 receptor, which belongs to the class B of the G protein-coupled receptor (GPCR) family, is a major therapeutic target in type 2 diabetes. Through its receptor, GLP-1 potentiates glucose-induced insulin secretion and improves the survival of pancreatic beta cells. Glucocorticoids are stress hormones implied in energetic metabolism and are widely used in therapeutics for their anti-inflammatory, immunosupressive and anti-allergic properties. Neverless, on chronic administration, glucocorticoids can induce metabolic syndrome especially due beta cell functional mass impairement. Here, we characterized the impact of a prolonged exposure of pancreatic beta cells to a synthetic glucocorticoid (dexamethasone) on biological actions of glucose and GLP-1.We show that a chronic exposure of beta cells to dexamethasone exerted deleterious effects on glucose-induced insulin secretion and ERK1/2 (Extracelllular Regulated Kinases 1/2) activation. In contrast, we observed that the glucocorticoid treatment increased GLP-1 receptor expression at the plasma membrane and improved the Galpha s protein coupling leading to an enhancement of cAMP production (2 fold increase). Despite the negative impact on glucose effects, glucocorticoids did not impair neither GLP-1-induced insulin secretion nor ERK1/2 activation. This study reveals that a glucocorticoid chronic exposure 1) regulates GLP-1 receptor trafficking and increases its expression to the plasma membrane, 2) causes supersensitization of Gαs-associated signaling, and 3) could impact on therapeutic effects of GLP-1 receptor-based drugs.; Les cellules béta pancréatiques synthétisent et sécrètent l’insuline, unique hormone hypoglycémiante de l’organisme. Ces cellules jouent un rôle central dans l’apparition du diabète, préserver leurs masses fonctionnelles est donc essentiel. Le récepteur GLP-1, appartenant à la classe B de la super famille des récepteurs couplés aux protéines G (RCPGs), est considéré comme une cible thérapeutique majeure dans le traitement du diabète de type 2. Via son récepteur, le GLP-1 potentialise la sécrétion d’insuline en réponse au glucose et favorise la survie des cellules beta. Les glucocorticoïdes sont des hormones du stress impliquées dans la régulation énergétique, largement utilisés en thérapeutique pour leur propriétés anti-inflammatoire, immunosuppresseur et antiallergique. Néanmoins, les glucocorticoïdes administrés en chronique sont diabétogènes en exerçant notamment des effets délétères sur les cellules beta. Nous avons caractérisé l’impact d’une exposition prolongée des cellules beta à un glucocorticoïde de synthèse (la dexaméthasone) sur les actions biologiques du glucose et du GLP-1. Nous montrons qu’une exposition prolongée des cellules beta à la dexaméthasone exerce des effets délétères en inhibant la sécrétion d’insuline en réponse au glucose et l’activation des kinases de survie ERK1/2 (Extracellular Regulated Kinases 1/2). A l’inverse, nous démontrons que l’exposition prolongée des cellules bêta à la dexaméthasone favorise le maintien du récepteur GLP-1 à la membrane plasmique, augmente le couplage du récepteur à la protéine Galpha s, ce qui se traduit par une production de second messager (AMPc) intracellulaire doublée. Malgré une diminution des effets du glucose, la sécrétion d’insuline et l’activation des kinases ERK1/2 en réponse au GLP-1 ne sont pas affectées. Cette étude révèle qu’une exposition chronique des cellules beta aux glucocorticoïdes 1) régule le trafficking du récepteur GLP-1 et favorise son maintien à la surface cellulaire, 2) hypersensibilise la signalisation du récepteur GLP-1 dépendante de la protéine Gαs , et 3) pourrait impacter les effets thérapeutiques des molécules ciblant l’activation du récepteur GLP-1.