Colitis ulcerosa (CU) und Morbus Crohn (MC) zählen zur Gruppe der chronischen Darmerkrankungen (CED). Im Gegensatz zu CU lässt sich bei MC eine transmurale Entzündung und eine Ummantelung des entzündeten Dünndarms mit mesenterialen Fettgewebe, dem sogenannten “creeping fat”, feststellen. In dieser Arbeit wurden zwei verschiedene Mechanismen der Immunregulation in der Pathogenese von CED untersucht: 1) Der SOCE-Signalweg (store-operated Ca2+ entry) stellt eine wichtige Signalkaskade dar, die die Aktivierung von T-Zellen steuert. Wir haben die Auswirkung einer pharmakologischen Blockade von SOCE auf die Funktion von Immunzellen untersucht, die aus der intestinalen Mukosa therapierefraktärer CED-Patienten isoliert wurden. Anschließend konnten wir die Sicherheit einer systemischen Verabreichung von SOCE-Inhibitoren in vivo im einem murinen IBD-Modell bestätigen und zeigen, dass die Blockade von SOCE eine therapeutische Option für die Behandlung von CED darstellen könnte. 2) Darüber hinaus untersuchten wir, ob das Fehlen von Fettgewebe eine entzündungsfördernde oder -hemmende Rolle bei der Entstehung von CED spielt. Daher wurde die Zusammensetzung des mukosalen Immunsystems sowie die Funktion der intestinalen Epithelbarriere in einem Mausmodell mit Adipozytenatrophie sowohl im steady-state als auch nach induzierter Kolitis verglichen. Wir konnten zeigen, dass eine Fettgewebsatrophie vor dem Ausbruch einer Kolitis schützt, und führte zu einer erhöhten Resistenz der intestinalen Barriere. Schließlich verglichen wir die Merkmale des lipoatrophischen Mausmodells mit denen eines seltenen Patienten mit erworbener Lipodystrophie und MC und kamen zu dem Schluss, dass die chirurgische Resektion von mesenterialen Fettgewebes für Patienten mit einem MC, bei denen eine intestinale Resektionen durchgeführt wird, sinnvoll sein könnte. / Inflammatory bowel disease (IBD) is a group of chronic intestinal autoimmune disorders, including ulcerative colitis (UC) and Crohn's disease (CD). In contrast to UC, CD is characterized by transmural inflammation and mesenteric adipose tissue wrapping the inflamed small intestine, known as "creeping fat." Despite all currently available drug therapies, treating IBD remains a major challenge, underlying the necessity of identifying new therapeutic targets. In this work, two different mechanisms of immune regulation in the pathogenesis of IBD were investigated: First, because the store-operated Ca2+ entry (SOCE) signaling pathway is a crucial Ca2+ signaling cascade for T cell activation, we investigated the effect of pharmacological SOCE-blockade on intestinal immune cells isolated from therapy refractory IBD patients. Subsequently, we confirmed the efficacy and safety of systemic administration of SOCE inhibitors in vivo in an IBD murine model, demonstrating that the blockade of SOCE may represent a therapeutic option for treating IBD. Second, we investigated whether adipose tissue plays a pro- or anti-inflammatory role in the development of IBD. Therefore, we characterized the mucosal immune system and intestinal epithelial barrier in a murine model affected by adipocyte atrophy both at steady-state and after induction of colitis. We demonstrated that lipodystrophy protected against the onset of colitis and increased intestinal barrier resistance. Finally, we compared the lipoatrophic mouse model with a rare patient with acquired generalized lipodystrophy and CD, concluding that adipokines might play a pro-inflammatory role in IBD. Therefore, we suggest that surgical resection of mesenteric adipose tissue in CD patients might be a beneficial intervention in patients undergoing bowel resection.

INTRODUÇÃO: A Moléstia de Dupuytren (MD) é uma doença crônica progressiva fibroproliferativa caracterizada por contraturas em flexão dos dedos. A origem deste processo está na proliferação de miofibroblastos e na síntese de matriz extracelular. Diversas técnicas já foram descritas no tratamento da MD. A falta de uma técnica capaz de associar altas taxas de sucesso com baixos índices de complicações e recidivas estimulou a procura por novas técnicas. Acredita-se que a propriedade totipotente das células-tronco presentes no tecido adiposo seria capaz de atuar na proliferação e na diferenciação dos fibroblastos em miofibroblastos, interrompendo a formação da fibrose e consequentemente a progressão da deformidade dos dedos. OBJETIVO: O objetivo primário deste estudo foi avaliar o efeito do enxerto de gordura, rico em células-tronco, nos pacientes com MD, submetidos a fasciectomia parcial aberta, por meio de avaliação funcional e goniométrica, e comparar com a técnica convencional (sem adição de enxerto de gordura). MÉTODO: Dois grupos totalizando 45 pacientes (24 pacientes no Grupo Controle e 21 no Grupo com gordura) foram operados pela técnica da fasciectomia parcial aberta. No Grupo controle era realizada apenas a fasciectomia parcial aberta. No Grupo com gordura, era realizada a fasciectomia parcial aberta e injetado, no local da corda ressecada, o enxerto de gordura, após o processamento do lipoaspirado de adipócitos proposto por Coleman (2006). O estudo foi prospectivo, randomizado e terapêutico. Os desfechos foram avaliados pela medida goniométrica do Déficit de Extensão Passiva Total (DEPT) e pelo escore funcional Brief Michigan Hand Questionnaire (BMHQ). As avaliações eram feitas no pré-operatório, com 6 semanas, 6 meses, 1 ano e 2 anos de seguimento. RESULTADOS: Na comparação com 6 semanas de pós-operatório, houve um aumento significativo da dor no Grupo com Gordura [mediana 2 ± 2,82 versus 0 ± 1,86 no grupo Controle (p=0,045)]. Os resultados do DEPT, não mostraram diferença significativa entre os grupos. Observamos piores resultados do escore funcional BMHQ com 6 meses e 1 ano de pós-operatório no Grupo com gordura (p=0,040 e p=0,047, respectivamente). Observamos ainda 9 casos (43%) de complicações no Grupo com gordura e 2 (8%) no Grupo Controle (p=0,019). CONCLUSÃO: O uso do enxerto de gordura associado à fasciectomia parcial aberta promoveu piores resultados funcionais comparado com a fasciectomia parcial aberta convencional, no curto prazo (um ano de seguimento pós-operatório). No entanto, resta a dúvida de qual seriam os resultados a longo prazo e, se as células-tronco, presentes no enxerto de gordura, poderiam interferir na recidiva da doença futuramente / BACKGROUND: Dupuytren\'s disease (DD) is a progressive chronic fibroproliferative disease characterized by flexion contractures of the fingers. The origin of this process is the proliferation of myofibroblasts and extra-cellular matrix synthesis. Several techniques have been described to treat the DD. The lack of a technique capable to associate high success rates with low rates of complications and recurrence stimulated the search for new techniques. It is believed that the totipotent property of the adipose-derived stem cells present in the processed lipoaspirate tissue would be able to inhibit the proliferation and differentiation of fibroblasts in myofibroblasts, interrupting the formation of fibrosis and consequently the progression of finger deformity. The primary objective of this study was to evaluate the effect of adipose-derived stem cells in patients with DD who underwent to open limited fasciectomy and compare with the conventional technique of limited fasciectomy. METHODS: A total of 45 patients were assigned in two groups in a single blind, prospective, randomized, controlled trial. All the patients were treated by the limited fasciectomy technique. In the control group (24 patients), only limited fasciectomy was performed. In the study group (21 patients), after the limited fasciectomy procedure, autologous lipoaspirate was injected at the site of the resected cord. Outcomes were assessed by the Total Passive Extension Deficit (TPED) and by the Brief Michigan Hand Questionnaire (BMHQ) functional score. The evaluations were performed by occupational therapists in the preoperative and at 6 weeks, 6 months, 1 year and 2 years. RESULTS: The study group presented higher rates of pain at 6 weeks postoperative (median 2 ± 2,82 versus 0 ± 1,86 on control group, p=0,045). TPED showed no significant differences between groups. BMHQ score, at 6 months and 1 year after surgery, were significantly inferior in the study group (p=0,040 e p=0,047, respectively). Patients in the study group had higher incidence of complications (9 patients, 43% versus 2, 8% in the control group, p=0,019). CONCLUSIONS: The autologous lipoaspirate associated to limited fasciectomy demonstrates inferior results regarding to functional score and pain compared to conventional limited fasciectomy, in short-term. Further long-term analysis is required to observe the effect of adipose-derived stem cells in the recurrences rates

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Este trabalho teve como objetivo investigar os efeitos da telmisartana (agonista PPAR-gama parcial), losartana (puro bloqueador do receptor AT1 da angiotensina II) e rosiglitazona (agonista PPAR-gama) em modelo experimental de síndrome metabólica. Os alvos do estudo foram a pressão arterial, metabolismo de carboidratos, resistência insulínica, inflamação, tecido adiposo e fígado. Camundongos C57BL/6 (a partir de 3 meses de idade) foram alimentados com dieta padrão (SC, n = 10) ou dieta hiperlipídica rica em sal (HFHS, n = 40) por 12 semanas. Após esse tempo, os animais do grupo HFHS foram subdivididos em 4 grupos (n = 10): HFHS (sem tratamento), ROSI (HFHS tratado com rosiglitazona), TELM (HFHS tratado com telmisartana) e LOS (HFHS tratado com losartana) por 5 semanas. O grupo HFHS apresentou um significante ganho de peso e aumento da pressão arterial sistólica, hiperinsulinemia com resistência insulínica, hiperleptinemia, hipertrofia de adipócitos bem como um quadro de esteatose hepática e níveis aumentados da citocina inflamatória interleucina-6 (IL-6). Os animais tratados com telmisartana chegou ao final do experimento com massa corporal similar ao grupo SC, com reversão do quadro de resistência insulínica, com pressão arterial normal, adipócitos de tamanho normal e sem apresentar esteatose hepática. Além disso, o tratamento com telmisartana aumentou a expressão de PPARγ e adiponectina no tecido adiposo epididimal. A expressão da proteína desacopladora-1 (UCP-1) no tecido adiposo branco (TAB) também foi aumentada. O tratamento com losartana diminuiu a pressão arterial para valores normais, porém com menores efeitos nos parâmetros metabólicos dos animais. O presente modelo experimental de ganho de peso e hipertensão induzidos por dieta mimetiza a síndrome metabólica humana. Neste modelo, a telmisartana aumentou a expressão de UCP-1 no TAB, preveniu o ganho de peso e melhorou a sensibilidade à insulina e a esteatose hepática dos camundongos C57BL/6, provavelmente devido à ativação PPAR-gama. / The study aimed to investigate the effects of telmisartan (a partial PPAR gamma agonist), losartan (a pure angiotensin II receptor blocker) and rosiglitazone (PPAR gamma agonist) in a mice model of metabolic syndrome (MetS). The targets of this study were blood pressure (BP), carbohydrate metabolism, insulin resistance, inflammation, white adipose tissue (WAT) and liver. Male C57BL/6 mice were studied over 17 weeks after being separated into two major groups according to diet: standard chow (SC, 10% fat, n = 10) or high-fat high-salt chow (HFHS, 60% fat, 7% salt, n = 40). In the last 5 weeks of the experiment, the HFHS group was divided into four groups (n = 10): untreated HFHS, ROSI (HFHS plus rosiglitazone), TELM (HFHS plus telmisartan), and LOS (HFHS plus losartan). The HFHS group had significantly greater body mass and BP, in addition to hyperinsulinemia with insulin resistance, hyperleptinemia, adipocyte hypertrophy and hepatic steatosis as well as increased inflammatory cytokine levels. Animals treated with telmisartan had body weights similar to the SC group, in addition to reversed insulin resistance, reduced hypertension, reduced adipocyte hypertrophy, ameliorates hepatic steatosis and decreased IL-6. Telmisartan increased PPARγ and adiponectin expression in white adipose tissue. Interestingly, the expression of UCP-1 in white adipose tissue was also increased by treatment with telmisartan. Losartan decreased BP but had smaller effects on metabolic parameters. The present model of diet-induced weight gain and hypertension in mice mimics human features of MetS. In this model, telmisartan enhances UCP-1 expression in WAT, prevented weight gain and ameliorates insulin sensitivity and hepatic steatosis in C57Bl/6 mice, probably due to PPAR gamma activation.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Este trabalho teve como objetivo investigar os efeitos da telmisartana (agonista PPAR-gama parcial), losartana (puro bloqueador do receptor AT1 da angiotensina II) e rosiglitazona (agonista PPAR-gama) em modelo experimental de síndrome metabólica. Os alvos do estudo foram a pressão arterial, metabolismo de carboidratos, resistência insulínica, inflamação, tecido adiposo e fígado. Camundongos C57BL/6 (a partir de 3 meses de idade) foram alimentados com dieta padrão (SC, n = 10) ou dieta hiperlipídica rica em sal (HFHS, n = 40) por 12 semanas. Após esse tempo, os animais do grupo HFHS foram subdivididos em 4 grupos (n = 10): HFHS (sem tratamento), ROSI (HFHS tratado com rosiglitazona), TELM (HFHS tratado com telmisartana) e LOS (HFHS tratado com losartana) por 5 semanas. O grupo HFHS apresentou um significante ganho de peso e aumento da pressão arterial sistólica, hiperinsulinemia com resistência insulínica, hiperleptinemia, hipertrofia de adipócitos bem como um quadro de esteatose hepática e níveis aumentados da citocina inflamatória interleucina-6 (IL-6). Os animais tratados com telmisartana chegou ao final do experimento com massa corporal similar ao grupo SC, com reversão do quadro de resistência insulínica, com pressão arterial normal, adipócitos de tamanho normal e sem apresentar esteatose hepática. Além disso, o tratamento com telmisartana aumentou a expressão de PPARγ e adiponectina no tecido adiposo epididimal. A expressão da proteína desacopladora-1 (UCP-1) no tecido adiposo branco (TAB) também foi aumentada. O tratamento com losartana diminuiu a pressão arterial para valores normais, porém com menores efeitos nos parâmetros metabólicos dos animais. O presente modelo experimental de ganho de peso e hipertensão induzidos por dieta mimetiza a síndrome metabólica humana. Neste modelo, a telmisartana aumentou a expressão de UCP-1 no TAB, preveniu o ganho de peso e melhorou a sensibilidade à insulina e a esteatose hepática dos camundongos C57BL/6, provavelmente devido à ativação PPAR-gama. / The study aimed to investigate the effects of telmisartan (a partial PPAR gamma agonist), losartan (a pure angiotensin II receptor blocker) and rosiglitazone (PPAR gamma agonist) in a mice model of metabolic syndrome (MetS). The targets of this study were blood pressure (BP), carbohydrate metabolism, insulin resistance, inflammation, white adipose tissue (WAT) and liver. Male C57BL/6 mice were studied over 17 weeks after being separated into two major groups according to diet: standard chow (SC, 10% fat, n = 10) or high-fat high-salt chow (HFHS, 60% fat, 7% salt, n = 40). In the last 5 weeks of the experiment, the HFHS group was divided into four groups (n = 10): untreated HFHS, ROSI (HFHS plus rosiglitazone), TELM (HFHS plus telmisartan), and LOS (HFHS plus losartan). The HFHS group had significantly greater body mass and BP, in addition to hyperinsulinemia with insulin resistance, hyperleptinemia, adipocyte hypertrophy and hepatic steatosis as well as increased inflammatory cytokine levels. Animals treated with telmisartan had body weights similar to the SC group, in addition to reversed insulin resistance, reduced hypertension, reduced adipocyte hypertrophy, ameliorates hepatic steatosis and decreased IL-6. Telmisartan increased PPARγ and adiponectin expression in white adipose tissue. Interestingly, the expression of UCP-1 in white adipose tissue was also increased by treatment with telmisartan. Losartan decreased BP but had smaller effects on metabolic parameters. The present model of diet-induced weight gain and hypertension in mice mimics human features of MetS. In this model, telmisartan enhances UCP-1 expression in WAT, prevented weight gain and ameliorates insulin sensitivity and hepatic steatosis in C57Bl/6 mice, probably due to PPAR gamma activation.

INTRODUÇÃO: A Moléstia de Dupuytren (MD) é uma doença crônica progressiva fibroproliferativa caracterizada por contraturas em flexão dos dedos. A origem deste processo está na proliferação de miofibroblastos e na síntese de matriz extracelular. Diversas técnicas já foram descritas no tratamento da MD. A falta de uma técnica capaz de associar altas taxas de sucesso com baixos índices de complicações e recidivas estimulou a procura por novas técnicas. Acredita-se que a propriedade totipotente das células-tronco presentes no tecido adiposo seria capaz de atuar na proliferação e na diferenciação dos fibroblastos em miofibroblastos, interrompendo a formação da fibrose e consequentemente a progressão da deformidade dos dedos. OBJETIVO: O objetivo primário deste estudo foi avaliar o efeito do enxerto de gordura, rico em células-tronco, nos pacientes com MD, submetidos a fasciectomia parcial aberta, por meio de avaliação funcional e goniométrica, e comparar com a técnica convencional (sem adição de enxerto de gordura). MÉTODO: Dois grupos totalizando 45 pacientes (24 pacientes no Grupo Controle e 21 no Grupo com gordura) foram operados pela técnica da fasciectomia parcial aberta. No Grupo controle era realizada apenas a fasciectomia parcial aberta. No Grupo com gordura, era realizada a fasciectomia parcial aberta e injetado, no local da corda ressecada, o enxerto de gordura, após o processamento do lipoaspirado de adipócitos proposto por Coleman (2006). O estudo foi prospectivo, randomizado e terapêutico. Os desfechos foram avaliados pela medida goniométrica do Déficit de Extensão Passiva Total (DEPT) e pelo escore funcional Brief Michigan Hand Questionnaire (BMHQ). As avaliações eram feitas no pré-operatório, com 6 semanas, 6 meses, 1 ano e 2 anos de seguimento. RESULTADOS: Na comparação com 6 semanas de pós-operatório, houve um aumento significativo da dor no Grupo com Gordura [mediana 2 ± 2,82 versus 0 ± 1,86 no grupo Controle (p=0,045)]. Os resultados do DEPT, não mostraram diferença significativa entre os grupos. Observamos piores resultados do escore funcional BMHQ com 6 meses e 1 ano de pós-operatório no Grupo com gordura (p=0,040 e p=0,047, respectivamente). Observamos ainda 9 casos (43%) de complicações no Grupo com gordura e 2 (8%) no Grupo Controle (p=0,019). CONCLUSÃO: O uso do enxerto de gordura associado à fasciectomia parcial aberta promoveu piores resultados funcionais comparado com a fasciectomia parcial aberta convencional, no curto prazo (um ano de seguimento pós-operatório). No entanto, resta a dúvida de qual seriam os resultados a longo prazo e, se as células-tronco, presentes no enxerto de gordura, poderiam interferir na recidiva da doença futuramente / BACKGROUND: Dupuytren\'s disease (DD) is a progressive chronic fibroproliferative disease characterized by flexion contractures of the fingers. The origin of this process is the proliferation of myofibroblasts and extra-cellular matrix synthesis. Several techniques have been described to treat the DD. The lack of a technique capable to associate high success rates with low rates of complications and recurrence stimulated the search for new techniques. It is believed that the totipotent property of the adipose-derived stem cells present in the processed lipoaspirate tissue would be able to inhibit the proliferation and differentiation of fibroblasts in myofibroblasts, interrupting the formation of fibrosis and consequently the progression of finger deformity. The primary objective of this study was to evaluate the effect of adipose-derived stem cells in patients with DD who underwent to open limited fasciectomy and compare with the conventional technique of limited fasciectomy. METHODS: A total of 45 patients were assigned in two groups in a single blind, prospective, randomized, controlled trial. All the patients were treated by the limited fasciectomy technique. In the control group (24 patients), only limited fasciectomy was performed. In the study group (21 patients), after the limited fasciectomy procedure, autologous lipoaspirate was injected at the site of the resected cord. Outcomes were assessed by the Total Passive Extension Deficit (TPED) and by the Brief Michigan Hand Questionnaire (BMHQ) functional score. The evaluations were performed by occupational therapists in the preoperative and at 6 weeks, 6 months, 1 year and 2 years. RESULTS: The study group presented higher rates of pain at 6 weeks postoperative (median 2 ± 2,82 versus 0 ± 1,86 on control group, p=0,045). TPED showed no significant differences between groups. BMHQ score, at 6 months and 1 year after surgery, were significantly inferior in the study group (p=0,040 e p=0,047, respectively). Patients in the study group had higher incidence of complications (9 patients, 43% versus 2, 8% in the control group, p=0,019). CONCLUSIONS: The autologous lipoaspirate associated to limited fasciectomy demonstrates inferior results regarding to functional score and pain compared to conventional limited fasciectomy, in short-term. Further long-term analysis is required to observe the effect of adipose-derived stem cells in the recurrences rates

La transplantation rénale, thérapie de choix de l'insuffisance rénale chronique terminale, est limitée par une pénurie d'organes. Les greffons issus de donneurs décédés par arrêt cardiaque (DDAC) peuvent contribuer à pallier à cette pénurie au prix de stratégies thérapeutiques visant à améliorer l'issue de la transplantation. Les cellules souches mésenchymateuses (MSC) de l'organisme adulte ont des propriétés de sécrétion, d'immunomodulation et de différenciation intéressantes dans ce contexte.L'objectif de ce travail est d'évaluer, dans un modèle pré-clinique porcin de DDAC, le potentiel thérapeutique de deux populations cellulaires d'intérêt : les MSC issues du liquide amniotique (AFSC) et les cellules de la fraction vasculaire stromale du tissu adipeux (SVF). Les AFSC porcines injectées dans l'artère rénale 7 jours post-greffe, en raison de leur sensibilité à une séquence d'hypoxie réoxygénation (HR) in vitro, accélèrent la reprise de fonction et réduisent l'extension des lésions chroniques du greffon et sont détectées dans le rein 24h après injection. La SVF porcine, phénotypiquement proche de celle de l'Homme, est moins sensible à cette séquence d'HR et peut être injectée dans l'artère du greffon à sa reperfusion sans perturbation du flux sanguin rénal, avec une rétention des cellules dans le rein 24h post injection.Ce travail met en évidence le rôle bénéfique des AFSC dans la réparation des lésions ischémie-reperfusion des greffons issus des DDAC, ainsi que la faisabilité de l'injection de la SVF dans l'artère rénale après transplantation, et ouvre des pistes pour l'optimisation les protocoles d'administration de produits de thérapie cellulaire en transplantation. / Kidney transplantation is the best therapeutic option for end stage chronic kidney failure, but is limited by transplant shortage. Use of transplants from deceased after cardiac death donors (DCD) could represent an additional graft source, but there is a need for developing new therapeutic approaches like cell therapy to increase their recovery. Mesenchymal stem cells (MSC) potentially extracted from many adult tissues have interesting paracrine, immune-modulating, and differentiation properties in this context. This work aims to assess, in a preclinical porcine model DCD donor, the therapeutic potential of two cell populations of interest: amniotic fluid derived MSC (AFSC) and cells from stromal vascular fraction of adipose tissue (SVF). Delayed injection of AFSC 7 days following kidney transplantation because of their sensitivity to a specific Hypoxia Reoxygenation (HR) sequence in vitro, accelerates graft function recovery and limits chronic injuries to the transplanted organ. Cells are detectable into the transplanted kidney 24h after injection. Porcine SVF is phenotypically similar to human. Injected in renal artery simultaneously with organ reperfusion because of its resistance to the HR sequence, porcine SVF does not disturb renal blood flow and allow cell-retention within the organ 24h after injection. This work highlights the protective effect of AFSC against ischemia reperfusion lesions in grafts from DCD donors and the feasibility of SVF injection directly into the renal artery of the graft following kidney transplantation in DCD conditions. Moreover it opens new lines for optimizing injection protocols of cellular products in kidney transplantation.

L’obésité s’accompagne de pathologies comme le diabète de type 2 et les maladies cardiovasculaires, liées à des dérégulations métaboliques et endocriniennes du tissu adipeux blanc (TAB). Au cours du vieillissement, la perte de masse musculaire peut être associée à l’obésité et définit le concept d’obésité sarcopénique. Les traitements mis en œuvre pour contrecarrer ces pathologies n’ont qu’un succès très partiel. Il est donc opportun de développer des stratégies alternatives originales qui pourraient aboutir à des thérapeutiques ciblées. Notre équipe étudie les régulations métaboliques du TAB, source majeure de stockage de l’énergie de l’organisme. Les triglycérides stockés sont libérés à jeun grâce à la lipolyse qui libère les acides gras non-estérifiés (AGNE) et le glycérol dans le sang, comme source d’énergie des autres tissus. En plus de la β-oxydation des AGNE, leur ré-estérification partielle intervient pour limiter leur libération lors de la lipolyse. La glycéronéogenèse est nécessaire à la ré-estérification en situation de jeûne. Des études préalables ont montré que l'administration de citrulline (CIT) pendant trois mois à des rats vieillissants induit une diminution d’environ 40% de la masse viscérale du TAB. Cet acide aminé non protéique est un complément alimentaire donné au cours du vieillissement ou à des sportifs pour augmenter la masse musculaire. Nous avons étudié les effets de la CIT sur des cultures d’explants de TAB de rats. Dans la première partie de ce travail, nous montrons que la CIT a un effet direct lipolytique et anti-glycéronéogénique sur les explants des rats qu’ils soient jeunes ou âgés. Cependant, la libération des AGNE du TAB des rats jeunes est limitée par une augmentation de la capacité oxydative du tissu. Avec l’âge, la masse du TAB augmente en parallèle à l’augmentation d’un état pro-inflammatoire. Afin de comprendre l’influence de ces deux paramètres indépendamment de l’âge, nous avons étudié dans la deuxième partie de ce travail, les effets de la CIT sur les explants de TAB de rats jeunes soumis à un régime contrôle (CD) ou hyperlipidique (HFD). Nous observons une augmentation, induite par la CIT, de la lipolyse et de la capacité ß-oxydative du TAB des rats quel que soit le régime, alors que la glycéronéogenèse est diminuée. Toutefois, les AGNE sont sélectivement libérés par le TAB de rats HFD, en relation avec une réduction drastique de leur ré-estérification. Le NO est un médiateur de ces effets. Dans une troisième partie, nous démontrons que la CIT agit directement sur le TAB de rats CD et HFD pour induire l'expression de la protéine découplante, UCP1, en lien avec le « brunissement » potentiel du TAB par cet acide aminé. Ces effets ne sont pas observés au sein du TAB des rats âgés. L’ensemble de nos résultats établit les bases pour de futures investigations visant à élucider les mécanismes par lesquels la CIT réduit la masse adipeuse et ouvre de nouvelles perspectives thérapeutiques pour lutter contre le surpoids et l’obésité sarcopénique. / Obesity is frequently associated with type 2 diabetes and cardiovascular diseases, related to metabolic and endocrine dysregulation of white adipose tissue (WAT). During aging, the loss of muscle mass may be associated with obesity and defines the concept of sarcopenic obesity. Treatments implemented to counteract these conditions showed a very partial success. It is therefore appropriate to develop original alternative strategies that could lead to targeted therapies. Our team studies the metabolic regulation of WAT, the major source of energy storage in the body. Non-esterified fatty acids (NEFA) and glycerol are released in the blood from stored triglycerides through lipolysis and used as a source of energy for other tissues. In addition to their β-oxidation, NEFA are re-esterified in part, a process that limits their release in the blood. Glyceroneogenesis is the pathway necessary to NEFA re-esterification in the fasting state. Previous studies showed that administration of citrulline (CIT) for three months to aging rats induced a decrease of approximately 40% of the visceral WAT mass. This non-protein amino acid is given as a dietary supplement during aging or sports to increase muscle mass. We studied the effects of CIT on explant cultures of rat WAT. In the first part of this work, we show that CIT exerts a direct lipolytic and anti-glyceroneogenic effect on explants from rats whether young or old. However, the release of NEFA from the explants of young rats is limited by an increase in the oxidative capacity of the tissue. During aging, WAT mass augments in parallel to the increase in a pro-inflammatory state. To understand the influence of these two parameters regardless of age, we studied in the second part of this work, the effects of CIT on WAT explants from young rats fed a control (CD) or high fat (HFD) diet. We show an CIT-induced increase in lipolysis and beta-oxidative capacity of WAT from rats whatever the diet, while glyceroneogenesis is reduced. However, NEFA are selectively released from WAT of HFD rats, in connection with a drastic reduction of their re-esterification. NO is a mediator of these effects. In the third part of this work, we show that CIT acts directly on WAT from CD and HFD rats to induce the expression of uncoupling protein, UCP1, in line with the potential "browning" of WAT by this amino acid. These effects were not observed in explants from old rats. Altogether our results establish the basis for future investigations aimed at elucidating the mechanisms by which CIT reduces body fat and open new therapeutic perspectives to fight overweight and sarcopenic obesity.

L’obésité est associée au développement de plusieurs complications métaboliques, dont la résistance à l’insuline (RI). Or, certains sujets obèses ne développent pas de RI. Ces obèses sensibles à l’insuline (ISO) représentent un modèle humain unique pour étudier les facteurs impliqués dans le développement de la RI. La fibrose du tissu adipeux a été directement associée au développement de la RI chez le rongeur. Nous avons donc évalué la fibrose dans les tissus adipeux sous-cutané (TASC) et viscéral (TAV) d’individus obèses ISO, résistants à l’insuline (IRO) et diabétiques de type 2 (DT2), avant et six mois après leur chirurgie bariatrique. Malgré un âge, IMC et pourcentage de masse grasse semblables, les ISO présentaient une RI inférieure à celle des IRO avant la chirurgie (p < 0,05). Aucune différence n’a été observée entre les sujets ISO, IRO et DT2 en ce qui concerne la fibrose totale et les niveaux d’expression de gènes associés à la fibrose, ni dans le TASC ni dans le TAV. Toutefois, le log du pourcentage de fibrose dans le TASC était positivement corrélé avec le log de HOMA-IR (r = 0,3847, p = 0,0476) avant la chirurgie. Six mois plus tard, les niveaux de fibrose demeurent inchangés dans le TASC, mais la RI est significativement réduite dans tous les groupes, particulièrement chez les DT2. Aucune corrélation n’a été observée entre la fibrose du TASC et l’HOMA-IR après la chirurgie. Ces résultats montrent une association significative, mais éphémère entre la fibrose du TASC et la RI chez l’humain obèse. / Obesity is associated to the development of metabolic complications, including insulin resistance. Yet, a distinctive subset of obese patients seems protected from insulin resistance. Such insulin-sensitive obese subpopulation (ISO) offers a unique opportunity to investigate factors underlying the development of insulin resistance in humans without the confounding effect of major differences in adiposity. Adipose tissue fibrosis has been directly linked to the development of obesity-associated insulin resistance in rodents. Therefore, we quantified total fibrosis and examined the expression of fibrosis-related genes in subcutaneous (SAT) and visceral (VAT) adipose tissue biopsies of diabetic (T2D) and non diabetic obese patients stratified into ISO or insulin-resistant obese (IRO) based on the OGTT-derived ISIMatsuda index, before and six months after bariatric surgery. Despite similar age, BMI, and percent fat mass, ISO had lower insulin resistance than IRO subjects (p<0.05) at baseline. No difference was found between ISO, IRO and T2D, neither in terms of total fibrosis, nor in the expression of fibrosis-related genes in the adipose tissues before surgery. However, log SAT fibrosis positively correlated with log HOMA-IR at baseline (r = 0.3847, p < 0.05). Six months after surgery, fibrosis levels remained unchanged in SAT, but insulin resistance was significantly reduced in all groups, especially in T2D patients. No correlation was found between SAT fibrosis and HOMA-IR after surgery. These results show a significant, yet ephemeral association between SAT fibrosis and insulin resistance in obese humans.

No description available.

L’obésité s’accompagne de pathologies comme le diabète de type 2 et les maladies cardiovasculaires, liées à des dérégulations métaboliques et endocriniennes du tissu adipeux blanc (TAB). Au cours du vieillissement, la perte de masse musculaire peut être associée à l’obésité et définit le concept d’obésité sarcopénique. Les traitements mis en œuvre pour contrecarrer ces pathologies n’ont qu’un succès très partiel. Il est donc opportun de développer des stratégies alternatives originales qui pourraient aboutir à des thérapeutiques ciblées. Notre équipe étudie les régulations métaboliques du TAB, source majeure de stockage de l’énergie de l’organisme. Les triglycérides stockés sont libérés à jeun grâce à la lipolyse qui libère les acides gras non-estérifiés (AGNE) et le glycérol dans le sang, comme source d’énergie des autres tissus. En plus de la β-oxydation des AGNE, leur ré-estérification partielle intervient pour limiter leur libération lors de la lipolyse. La glycéronéogenèse est nécessaire à la ré-estérification en situation de jeûne. Des études préalables ont montré que l'administration de citrulline (CIT) pendant trois mois à des rats vieillissants induit une diminution d’environ 40% de la masse viscérale du TAB. Cet acide aminé non protéique est un complément alimentaire donné au cours du vieillissement ou à des sportifs pour augmenter la masse musculaire. Nous avons étudié les effets de la CIT sur des cultures d’explants de TAB de rats. Dans la première partie de ce travail, nous montrons que la CIT a un effet direct lipolytique et anti-glycéronéogénique sur les explants des rats qu’ils soient jeunes ou âgés. Cependant, la libération des AGNE du TAB des rats jeunes est limitée par une augmentation de la capacité oxydative du tissu. Avec l’âge, la masse du TAB augmente en parallèle à l’augmentation d’un état pro-inflammatoire. Afin de comprendre l’influence de ces deux paramètres indépendamment de l’âge, nous avons étudié dans la deuxième partie de ce travail, les effets de la CIT sur les explants de TAB de rats jeunes soumis à un régime contrôle (CD) ou hyperlipidique (HFD). Nous observons une augmentation, induite par la CIT, de la lipolyse et de la capacité ß-oxydative du TAB des rats quel que soit le régime, alors que la glycéronéogenèse est diminuée. Toutefois, les AGNE sont sélectivement libérés par le TAB de rats HFD, en relation avec une réduction drastique de leur ré-estérification. Le NO est un médiateur de ces effets. Dans une troisième partie, nous démontrons que la CIT agit directement sur le TAB de rats CD et HFD pour induire l'expression de la protéine découplante, UCP1, en lien avec le « brunissement » potentiel du TAB par cet acide aminé. Ces effets ne sont pas observés au sein du TAB des rats âgés. L’ensemble de nos résultats établit les bases pour de futures investigations visant à élucider les mécanismes par lesquels la CIT réduit la masse adipeuse et ouvre de nouvelles perspectives thérapeutiques pour lutter contre le surpoids et l’obésité sarcopénique. / Obesity is frequently associated with type 2 diabetes and cardiovascular diseases, related to metabolic and endocrine dysregulation of white adipose tissue (WAT). During aging, the loss of muscle mass may be associated with obesity and defines the concept of sarcopenic obesity. Treatments implemented to counteract these conditions showed a very partial success. It is therefore appropriate to develop original alternative strategies that could lead to targeted therapies. Our team studies the metabolic regulation of WAT, the major source of energy storage in the body. Non-esterified fatty acids (NEFA) and glycerol are released in the blood from stored triglycerides through lipolysis and used as a source of energy for other tissues. In addition to their β-oxidation, NEFA are re-esterified in part, a process that limits their release in the blood. Glyceroneogenesis is the pathway necessary to NEFA re-esterification in the fasting state. Previous studies showed that administration of citrulline (CIT) for three months to aging rats induced a decrease of approximately 40% of the visceral WAT mass. This non-protein amino acid is given as a dietary supplement during aging or sports to increase muscle mass. We studied the effects of CIT on explant cultures of rat WAT. In the first part of this work, we show that CIT exerts a direct lipolytic and anti-glyceroneogenic effect on explants from rats whether young or old. However, the release of NEFA from the explants of young rats is limited by an increase in the oxidative capacity of the tissue. During aging, WAT mass augments in parallel to the increase in a pro-inflammatory state. To understand the influence of these two parameters regardless of age, we studied in the second part of this work, the effects of CIT on WAT explants from young rats fed a control (CD) or high fat (HFD) diet. We show an CIT-induced increase in lipolysis and beta-oxidative capacity of WAT from rats whatever the diet, while glyceroneogenesis is reduced. However, NEFA are selectively released from WAT of HFD rats, in connection with a drastic reduction of their re-esterification. NO is a mediator of these effects. In the third part of this work, we show that CIT acts directly on WAT from CD and HFD rats to induce the expression of uncoupling protein, UCP1, in line with the potential "browning" of WAT by this amino acid. These effects were not observed in explants from old rats. Altogether our results establish the basis for future investigations aimed at elucidating the mechanisms by which CIT reduces body fat and open new therapeutic perspectives to fight overweight and sarcopenic obesity.