Hodgkin lymphoma (HL) is a heterogeneous condition varying from engaging one single lymph node site to a widespread condition. The prognosis with contemporary treatment is excellent for the vast majority. However, the treatment might cause severe late adverse effects in a proportion of the affected individuals. We evaluated all children and adolescents diagnosed in Sweden and registered in the Swedish Childhood Cancer Register over a period of 25 years. The incidence has been stable and the overall survival (OS) is very good, comparable to the best results in the world. Approximately ten percent encountered a relapse, but even after relapse the chances of survival were good. During the study period there were no detectable changes in survival estimates. The use of radiotherapy has decreased. Epstein Barr virus (EBV) and numbers of eosinophils, mast cells and macrophages in the tumors were investigated in 98 cases. Young children were more likely to express EBV. In patients with advanced disease the mast cell and macrophage counts were higher and they also had more affected laboratory parameters. Patients with Nodular Lymphocyte Predominant Hodgkin Lymphoma did not express EBV in the tumor, had significantly lower numbers of eosinophils, mast cells and macrophages and less affected laboratory parameters compared to classical HL. Outcome and clinical presentation were investigated in a cohort of children, adolescents and young adults in Sweden and Denmark and treatment in pediatric and adult departments was compared. OS and event-free survival (EFS) did not differ between the three age groups nor between pediatric and adult treatment. However, the Danish pediatric patients had lower EFS, which corresponded to less use of radiotherapy. Adolescents and young adults shared similar characteristics, while children presented differently with less advanced disease and male preponderance. Hospitalization rates and outpatient visits after end of treatment were evaluated to see whether the excess need of resources described in the literature is evenly distributed among the survivors or whether it is limited to a smaller group. Most of the patients had a low burden of health care use and the relapsing patients were the main drivers of the excess need.

Die Anaphylaxie, eine potentiell lebensbedrohliche Reaktion, kann durch Kofaktoren beeinflusst werden. ACE-Inhibitoren, ß-Blocker und Acetylsalicylsäure (ASS) werden häufig in der Therapie von Herz-Kreislauferkrankungen eingesetzt. In der vorliegenden Arbeit wurde überprüft, ob diese anaphylaktische Reaktionen begünstigen. Das Modell der passiv systemischen Anaphylaxie (PSA) wurde speziell angepasst, um die Behandlung einer Herz-Kreislauf-Therapie nachzubilden. Die orale Gabe von Metoprolol oder Ramipril verstärkte die Anaphylaxie geringfügig. Die Kombination der Medikamente steigerte die Anaphylaxie deutlich, was im Modell der passiv kutanen Anaphylaxie (PCA) bestätigt werden konnte. Gleichzeitig waren Mastzellmediatoren im Serum der Tiere erhöht. Die Inkubation muriner Mastzellen (MZ) mit den Medikamenten, steigerte die FcεRI-vermittelten Histaminfreisetzung in vitro. ASS-Vorbehandlung der Mäuse verstärkte die Ausprägung der PSA und der PCA, was mit einer Steigerung von MZ-Mediatoren im Serum assoziiert war. Die FcεRI-induzierte Histaminfreisetzung muriner MZ wurde hingegen nach ASS-Inkubation gehemmt, was auf einen indirekten Mechanismus hinweist. Die Reduktion der Prostaglandine (PG) durch ASS ist mit einer gesteigerten Leukotriensynthese verbunden. Der Leukotrienantagonist Montelukast konnte die, durch ASS verstärkte, PSA nicht mildern, was zeigt, dass dieser Effekt unabhängig von Leukotrienen ist. PGE2 kann die MZ-Degranulation über EP1-EP4-Rezeptoren modulieren. Tatsächlich schwächten EP3- und EP4-Rezeptoragonisten die durch ASS gesteigerte Anaphylaxie ab. PGE2 nimmt somit eine wichtige Rolle in der pro-anaphylaktischen Wirkung von ASS ein. Zusammenfassend wurde erstmals gezeigt, dass Metoprolol und Ramipril die Anaphylaxie über eine Steigerung der MZ-Reaktivität verstärken. ASS hingegen erhöht anaphylaktische Reaktionen über einen indirekt steigernden Effekt auf die MZ. PGE2 ist zumindest teilweise an der pro-anaphylaktischen Wirkung von ASS beteiligt. / Cofactors contribute to the severity of anaphylaxis, a potential life-threatening hypersensitivity reaction. ACE-inhibitors, ß-blockers and acetylsalicylic acid (asa) are frequently used drugs in cardiovascular therapy. Whether they affect systemic anaphylactic reactions has been addressed within this thesis. To this aim, the passive systemic anaphylaxis model (PSA) was employed here and specially designed to mimic a long term treatment in cardiovascular therapy. The data demonstrate that oral treatment of mice with ramipril or metoprolol alone slightly aggravated anaphylaxis. However, the combination clearly potentiated anaphylactic reactions, which was also confirmed in the passive cutaneous anaphylaxis model (PCA). In line with this, elevated amounts of mast cell (MC) mediators were detected in mice sera upon combined drug treatment. In vitro, FcεRI-mediated histamine release of murine MCs was likewise enhanced by the respective drugs. Pre-treatment of mice with asa aggravated the symptoms of PSA and PCA; simultaneously MC-mediators in sera were elevated. In contrast, FcεRI-mediated histamine release of MCs was reduced by asa in vitro, pointing to an indirect mechanism. Asa reduces prostaglandins (PGs) and increases leukotriene synthesis. The leukotriene antagonist montelukast failed to attenuate PSA, aggravated by asa, suggesting that the pro-anaphylactic effect of asa might be independent of leukotrienes. PGE2 can modulate MC degranulation via EP1-EP4 receptor. Indeed, EP3 and EP4 receptor agonists alleviated anaphylaxis enhanced by asa. Therefore PGE2 might play an important role in the pro-anaphylactic effect of asa. In conclusion, the data demonstrate for the first time that metoprolol and ramipril exacerbate anaphylactic symptoms by a direct increase in MC reactivity. In contrast, asa aggravates anaphylactic reactions by priming MCs through an indirect mechanism. PGE2 is at least partly involved in this process.

Bei der Wundheilung und fibrosierenden Prozessen sowie bei der Urtikaria ist eine Mastzellvermehrung bekannt. Mastzellen (MZ) üben bei der Urtikaria eine Schlüsselfunktion aus und scheinen auch zum Bindegewebsumbau beizutragen. In humanem Narbengewebe (5-369 Tage alt) wurden MZ-Zahlen und MZ-Subpopulationen mittels Enzym- und Immunhistochemie im Vergleich zu normaler Haut untersucht. Außerdem wurden in Gewebsextrakten Aktivität und mRNA-Expression der MZ-Proteasen und in vitro ihre mitogene Wirkung auf Fibroblasten und Keratinozyten bestimmt. Zur Klärung von Mechanismen, die zur MZ-Vermehrung beitragen könnten, analysierten wir die Expression von MZ-Chemoattraktoren und MZ-Wachstumsfaktoren sowie ihrer Rezeptoren in humanem Narbengewebe (a), läsionaler und nicht-läsionaler Urtikariahaut (b) und in normaler Haut (c): SCF, c-Kit, NGF-R TrkA, NGF-R p75, GM-CSF, GM-CSF-R (a, b, c); NGF, TGF-(, TGF-(-R I, TGF-(-R II (a,c) mittels Immunhistochemie (a, b, c) und RT-PCR (a, c). Zusätzlich wurde die Expression der proentzündlichen Zytokine IL-3, -8, TNF-( untersucht (b, c). Tryptase und Chymase enthaltende MZ waren in Narben gegenüber normaler Haut signifikant vermindert ebenso wie Chymaseaktivität und -mRNA-Expression in Narbengewebsextrakten. Die Anzahl Tryptase-haltiger MZ war unverändert, obwohl Tryptaseaktivität und -mRNA in Narben vermehrt waren. Beide Proteasen erhöhten in vitro die mitogene Antwort von Fibroblasten, jedoch nicht von Keratinozyten. c-Kit+-MZ fanden sich in der mittleren und tiefen Dermis von Narben signifikant vermehrt. SCF, TGF-(, TGF-(-R I und II, NGF-R p75 und TrkA zeigten sich sowohl immunhistochemisch als auch in der RT-PCR in Narbengewebe hochreguliert im Vergleich zu normaler Haut, wohingegen NGF, GM-CSF und GM-CSF-R nur schwach exprimiert waren ohne Unterschied zwischen beiden Geweben. Mittels FACS-Analyse wurde erstmalig die Expression von TGF-(-R I und II auf isolierten Haut-MZ nachgewiesen. Im Gegensatz zu diesen Befunden waren in Urtikariagewebe SCF- und NGF-R p75-exprimierende Zellen vermindert im Vergleich zu normaler Haut. Die Zahl von c-Kit+-, NGF-R TrkA+-, GM-CSF+- und GM-CSF-R+ -Zellen zeigte sich unverändert. Hingegen war die Expression von IL-3 und TNF-( auf Endothelzellen in läsionaler und nicht-läsionaler Urtikariahaut signifikant hochreguliert. Die dargestellten Ergebnisse mit signifikanter Verminderung von Chymase- und Tryptase-haltigen MZ in humanem kutanen Narbengewebe sprechen für MZ-Degranulation nach Trauma. Nachfolgend findet sich in Narbengewebe eine Chymase--, Avidin--, Tryptase+-, c-Kit+-MZ-Subpopulation, am ehesten Folge einer Einwanderung und Proliferation von unreifen MZ oder MZ-Vorläufern, die von den vermehrt exprimierten Wachstumsfaktoren SCF und TGF-(, eventuell auch von NGF über seine vermehrt exprimierten Rezeptoren, induziert werden könnten. Neben NGF und TGF-( scheint auch SCF eine Rolle bei der Wundheilung zu spielen. Bei entzündlichen Hautkrankheiten unterschiedlicher Prägung wie Wundheilung und Urtikaria liegen offenbar verschiedenartige Regulationsmuster der MZ-Proliferation und -Differenzierung vor. Unsere Ergebnisse legen nahe, dass bei Trauma Feedbackmechanismen über Wachstumsfaktoren wie SCF, TGF-( und NGF und ihre Rezeptoren auf MZ ablaufen, bei der Urtikaria unter Mitberücksichtigung bereits bekannter Daten aus der Literatur vorzugsweise über eine Interaktion von Mast- und Endothelzellen. / In wound healing and fibrosing processes as well as in urticaria an increase of mast cells (MC) has been observed. MC are key-players in urticaria, and might also contribute to tissue repair. In human cutaneous scar tissue (5-369 days old) and normal skin MC dynamics and MC subtypes were analysed by enzyme- and immunohistochemistry. Moreover, the activity of the MC proteases in extracts of both tissues and their in vitro effect on the mitogenesis of fibroblasts and keratinocytes were assessed. To elucidate mechanisms involved in mast cell accumulation, expression of MC chemotaxins, MC growth factors and their receptors was evaluated comparing cutaneous scar tissue (a), lesional and non-lesional skin of urticaria (b) and normal skin (c): SCF, c-Kit, NGF-R TrkA, NGF-R p75, GM-CSF, GM-CSF-R (a, b, c); NGF, TGF-(, TGF-(-R I, TGF-(-R II (a,c) by immunohistochemistry (a, b, c) and by RT-PCR (a, c). Additionally, expression of proinflammatory cytokines (IL-3, -8, TNF-() was studied (b, c). Tryptase and chymase containing MC were markedly decreased in scars as well as chymase activity and mRNA expression, whereas overall numbers of tryptase containing MC did not differ from those in normal skin, although tryptase activity and mRNA expression were increased in scar extracts. Both proteases induced a dose-dependent mitogenic response in 3T3-fibroblasts, but not in HaCaT-keratinocytes. Numbers of c-Kit+ MC were significantly increased in the mid and lower dermis of scars. Furthermore, SCF, TGF-(, its receptors I and II, the NGF-R p75 and TrkA were shown to be upregulated in scars both by immunohistochemistry and by RT-PCR, while NGF, GM-CSF and the GM-CSF-R were only weakly expressed without differences between scar and normal tissue. In addition, expression of TGF-(-R I and II could be shown on isolated human skin MC by FACS-analysis. In contrast to these findings, SCF- and NGF-R p75-expressing cells in urticaria tissue were downregulated compared to normal skin. Numbers of c-Kit+, NGF-R TrkA+, GM-CSF+ and GM-CSF-R+ cells remained unchanged. However, IL-3 and TNF-( expression was upregulated on endothelial cells in lesional and non-lesional skin of urticaria. These data show that numbers of resident MCTC are very low in human cutaneous scars suggesting massive mediator release from these cells after wounding. Instead, scar tissue is populated by a chymase-, avidin-, tryptase+, c-Kit+ MC subpopulation that is reflecting most probably an immigration and / or proliferation of immature MC and their precursors which might be promoted by SCF and TGF-beta, possibly also NGF via its receptors. Next to TGF-( and NGF, also SCF seems to play a role in wound healing. Our findings suggest different regulation patterns of MC increase in inflammatory conditions of the skin. After wounding, feedback mechanisms via growth factors (SCF, TGF-(, possibly NGF) and their receptors on MC could be operative, while in urticaria in accordance with data from the literature interactions between MC and endothelial cells appear to be essential.

Les récepteurs activés par les proliférateurs de peroxysomes (PPARs) sont des facteurs de transcription impliqués dans la régulation du métabolisme lipidique et de la tolérance au glucose. Les PPARs contrôlent également l’inflammation associée à de multiples pathologies, dont la polyarthrite rhumatoide. Dans les travaux présentés dans ce manuscrit, nous avons comparé les potentialités anti-arthritiques, dans un modèle expérimental, de deux agonistes synthétiques de haute affinité pour deux isotypes de PPARs, PPARα et PPARγ. Nous avons démontré qu’un traitement avec un agoniste sélectif de PPARγ, la pioglitazone, en plus de diminuer la sévérité de l’arthrite expérimentale, réduisait la perte osseuse inflammatoire en préservant la micro-architecture osseuse. Nous avons mis en évidence que PPARγ, d’une part, régulait l’expression locale et systémique de l’interleukine-17 et de RANKL, et que, d’autre part, il inhibait l’expression du facteur de transcription RORγt, acteur majeur de la voie IL-17/Th17. Les animaux déficients pour PPARγ nous ont permis de confirmer son rôle majeur dans le développement du processus arthritique. En effet, ces animaux présentent tous et de façon spontanée une arthrite associée à une augmentation du nombre de mastocytes capables de produire l’IL-17 et leur propre facteur de différenciation, le SCF dans la synoviale inflammatoire. Enfin, nous avons discuté le lien possible entre l'arthrite inflammatoire et la mastocytose à la lumière de l’étude d’un cas clinique d’un patient atteint de polyarthrite rhumatoïde concomitante à une mastocytose systémique / Peroxisome proliferator-activated receptors (PPARs) are transcription factors implicated in lipid metabolism and glucose tolerance. Once activated by specific agonists, PPARs control inflammation associated with numerous diseases, notably Rheumatoid arthritis. The first study presented here aim to compare the anti-arthritic potency of two high-affinity synthetic agonists for PPARα and PPARγ in an experimental model. Then we focused on the effect of pioglitazone, a high-affinity synthetic agonists for PPARγ, and demonstrated that a per os treatment with this agonist not only reduced experimental arthritis but also inhibited partly inflammation-related bone loss by preserving bone microarchitecture. We pointed out that PPARγ, on one hand, regulated local and systemic expression of interleukine-17 (IL-17) and RANKL and on the other hand, inhibited expression of transcription factor RORγt, a main regulator of IL-17/Th17 pathway. Study of mice deficient for PPARγ confirmed its major role in the development of the arthritic process since these mice developed spontaneously arthritis. Of interest arthritis in these mice is associated with increased number of synovial mast cells able to produce IL-17 and their own differenciation factor, the SCF. Finally, we discussed the possible link between inflammatory arthritis and mastocytosis in a case report of a patient suffering from rheumatoid arthritis concomitant to systemic mastocytosis

Os mastócitos (MCs) estão presentes tanto no periodonto normal quanto inflamado, em diferentes quantidades e em vários locais. Nos últimos anos, a eficácia e a contribuição dos MCs em eliminar bactérias, através de sua atividade microbicida intracelular, estão se tornando cada vez mais reconhecidas. Assim, a partir de MCs murinos desafiados in vitro com o periodontopatógeno Aggregatibacter actinomycetemcomitans (ATCC 29523) por 3, 5, 10 e 24 horas, o presente estudo teve como objetivo investigar a capacidade microbicida intracelular de MCs, e comparar com a capacidade microbicida de macrófagos peritoneais murinos (MPs), considerados fagócitos profissionais, por meio da contagem das unidades formadoras de colônias. Além disso, avaliou-se a produção e liberação de mediadores microbicidas, óxido nítrico (NO) e peróxido de hidrogênio (H2O2), por meio do método colorimétrico de Griess e pela degradação de substratos fluorescentes, respectivamente. Para a análise estatística, foram utilizados os testes estatísticos ANOVA Fatorial seguido do teste de Tukey e teste de correlação de Pearson (p<0.05). Nossos resultados revelaram que os MCs foram capazes de eliminar eficientemente o periodontopatógeno, principalmente após 10h de desafio intracelular. Comparando-se a atividade microbicida dos dois tipos celulares, verificou-se, nos períodos de 3h e 5h de desafio, um menor percentual de colônias viáveis no interior de MPs, em comparação aos MCs. Inversamente, nos períodos de 10h e 24h, observaram-se menores valores percentuais de colônias intracelulares nos MCs em relação aos MPs. Além disso, a produção/liberação de NO bem como, em menor proporção, de H2O2 pelos MCs foram concordantes com a sua capacidade microbicida. Este é o primeiro estudo que demonstra a eficiente ação microbicida intracelular de MCs murinos contra Aggregatibacter actinomycetemcomitans, com produção e liberação de substâncias potencialmente bactericidas, e de forma mais eficaz que os macrófagos. Esses resultados sugerem a importância dessas células nos mecanismos de defesa presentes na doença periodontal induzida por placa dentobacteriana. / Mast cells (MCs) are present in both normal and inflamed periodontal tissues, in varying amounts and locations. Recently, MCs contribution in eliminating bacteria and its effectiveness, through its intracellular microbicidal activity, have been increasingly recognized. Thus, this study aimed to investigate the intracellular microbicide capacity of MCs, and compare it with the microbicide capacity of murine peritoneal macrophages (MPs), considered professional phagocytes, by counting the colony forming units. Both cell types were challenged in vitro with periodontopathogen Aggregatibacter actinomycetemcomitans (ATCC 29523) by 3, 5, 10 and 24 hours. Additionally, the production and release of microbicidal agents, nitric oxide (NO) and hydrogen peroxide (H2O2) were evaluated by means of colorimetric Griess method and by the degradation of fluorescent substrates, respectively. Statistical analysis was performed by ANOVA Factorial test followed by Tukey and Pearson\'s correlation test (p <0.05). Our results revealed that MCs are able to efficiently eliminate periodontopathogen, mainly after 10 hours of intracellular challenge. The microbicidal activity of both cell types, in 3 and 5 hours of challenge showed a lower percentage of viable colonies inside MPs, compared to MCs. Contradictorily, in 10 and 24 hours a lower percentage of intracellular colonies in MCs was observed in relation to MPs. Moreover, the production/release of NO and, in minor proportion, of H2O2 by MCs was in agreement with its microbicidal capacity. Therefore, this is the first report to describe the intracellular microicidal activity of murine MCs against Aggregatibacter actinomycetemcomitans, concerning production and release of potentially bactericidal substances, which is more effective than macrophages. These results suggest the importance of these cells in pathogenesis and defense mechanisms of biofilm-associated periodontal disease.

Este estudo teve por objetivos: a) caracterizar o influxo de leucócitos (LC) induzido pelo veneno de Bothrops moojeni (VBm); b) avaliar o papel dos mastócitos (MC) e da histamina neste evento; c) analisar a liberação de TXA2, PGD2, LTB4, MCP-1 e KC e d) avaliar a capacidade do VBm desgranular MC in vivo e in vitro. A injeção intraperitoneal de VBm, em camundongos, causou o recrutamento de LC e neutrofilia. O tratamento dos animais com cromoglicato aboliu o influxo de LC enquanto a difenidramina, ranitidina e a tioperamida, antagonistas da histamina, reduziram o influxo de neutrófilos. Ainda, o veneno induziu a liberação de PGD2, TXA2, LTB4, MCP-1 e de KC e causou a desgranulação de MC in vivo e a liberação de -hexosaminidase de MC in vitro. Em conclusão, o VBm induz influxo de LC para o local de sua injeção. Este efeito depende da histamina, via receptores H1, H2 e H4 e da desgranulação de MC, que decorre de ação direta do veneno nestas células. A neutrofilia e o TXA2, LTB4, MCP-1 e KC devem contribuir para o influxo de leucócitos causado pelo VBm. / In this study the effects of Bothrops moojeni venom (BmV) on the cellular component of inflammatory responses and the mechanisms involved in this effect were investigated. The effects of venom on peritoneal and circulating leukocyte numbers and on the release of inflammatory mediators, such as LTB4, TXA2, PGD2, MIP-1 and KC, were assessed. The role of both mast cells and histamine receptors in leukocyte recruitment induced by BmV was assessed by selected pharmacological treatments. BmV caused a marked infiltration of leukocytes (3-24 h) when injected into the peritoneal cavity of mice. Neutrophils (PMN) were the predominant cell type in the early stages of response whereas macrophages (MN) were accumulated from 3 up to 24 h. Moreover, BmV increased blood neutrophil numbers at 3 h after injection. The BmV-induced leukocyte influx was abrogated by cromoglicate and significantly reduced either by difenidramine or ranitidine or tioperamide, histamine H1, H2 and H4 receptor antagonists, respectively, at 6 h after injection. Significant increments in peritoneal levels of LTB4, TXA2, PGD2, MIP-1 and KC were detected at distinct periods of time after venom injection. In addition, BmV induced mast cell degranulation both in vivo and in vitro. In conclusion, obtained data demonstrated the ability of BmV induce leukocyte recruitment into the site of its injection. This effect is dependent on mast cell activation and degranulation, which may be due to a direct effect of venom on these cells, and is mediated at least in part by histamine via H1, H2 and H4 receptors. Moreover, the ability of venom to mobilize leukocytes from bone marrow reserve compartments and to release the chemotactic mediators TXA2, LTB4, MCP-1 and KC may be relevant for leukocyte infiltration.

Les mastocytes (MCs) sont issus des cellules hématopoïétiques multipotentes non engagées, CD34+, et jouent un rôle important dans l’initiation de la réponse immunitaire innée et adaptative, ainsi que dans les réactions allergiques IgE-dépendantes. Les mastocytoses sont des néoplasies myéloïdes caractérisées par une accumulation anormale et l'activation fréquente de mastocytes dans divers organes. Les organes généralement atteints sont la moelle osseuse, la peau, le foie et le tractus gastro-intestinal. Elles sont caractérisées dans l’immense majorité des cas par la présence de mutations acquises de la structure du récepteur KIT (plus particulièrement KIT D816V) qui induisent l’activation constitutive de ce récepteur à activité tyrosine kinase intrinsèque. Le traitement actuel de ces pathologies est décevant car la mutation KIT D816V résiste à la plupart des inhibiteurs de tyrosine kinases (ITKs).Dès le début de ma thèse, nous avons pu établir, à partir de cellules souches hématopoïétiques de sang de cordon humain normal cultivées à long terme en présence de stem cell factor (SCF), une nouvelle lignée mastocytaire humaine stable, dénommée ROSA KIT WT, restant strictement dépendante pour sa survie et sa prolifération du SCF, exprimant le récepteur de haute affinité aux IgE (FcεRI), et présentant un récepteur KIT de structure normale. Cette lignée, facile à cultiver en grandes quantités, permet d’envisager l’étude approfondie des évènements intracellulaires menant à l’activation mastocytaire IgE-dépendante et la mise au point de tests de criblage à haut débit dans le domaine de la thérapeutique anti-allergique et/ou anti-inflammatoire.Par ailleurs, afin de pouvoir étudier le rôle transformant des mutants de KIT retrouvés au cours des mastocytoses, nous avons transfecté les cellules ROSA KIT WT par des vecteurs lentiviraux apportant une construction codant pour le KIT muté en D816V ou le KIT muté Delta 417-419 insY. Nous avons ainsi obtenu deux nouvelles lignées mastocytaires humaines SCF-indépendantes, ROSA KIT D816V et ROSA KIT Delta 417-419 insY, pour lesquelles nous avons montré qu’il existe une activation constitutive de KIT, mais aussi de STAT5 et d’AKT. Ces deux lignées de pourront être utilisées soit pour étudier l’impact des mutations de KIT sur la signalisation intracellulaire, soit pour le criblage molécules à activité antiproliférative potentielle dirigées soit contre KIT muté, soit contre l'une ou l’autre des molécules intracellulaires impliquées dans la transduction du signal KIT muté / Mast cells are cells with ubiquitous tissue distribution, derived from CD34 + multipotent hematopoietic cells. These cells play a fundamental role in the initiation of innate and adaptive immune response and in IgE-dependent allergic reactions or in various inflammatory reactions.Mastocytosis is defined as a myeloproliferative neoplastic disorder, caused by an abnormal accumulation of mast cells in one or more organ systems. Mastocytosis presents in cutaneous and systemic forms. In patients with systemic mastocytosis, the most frequent point mutation is KIT D816V, whereas in pediatric patients, where the disease is usually restricted to the skin, different KIT defects have been detected, mostly in the extracellular portion of KIT.In a primary culture of mast cells made from precursors of one cord blood, we have successfully isolated a new human mast cell line called ROSA KIT WT with a phenotype and reactivity comparable to those of normal mast cells. This cell line is dependent on SCF for growth and expresses the KIT receptor wild. It is easy to grow in large quantities, to freeze and to activate by IgE-anti IgE couple or a couple of allergen and corresponding specific IgE. This cell line can be used to study pathophysiologic mechanisms of allergy and to develop and use high-throughput screening tests of molecules in search of anti-allergic properties.In addition, we transfected these cells by lentiviral vectors providing constructs encoding the mutated KIT D816V or the mutated KIT Delta 417-419 insY, two KIT abnormalities encountered in the course of mastocytosis. This allowed us to establish two new cell lines independent of SCF for proliferation, ROSA KIT D816V and ROSA KIT Delta417-419 insY, which are particularly easy to grow in large quantities, and whose phenotype is similar to that of abnormal mast cells during mastocytosis. These two cell lines can be used for pathophysiologic studies on mastocytosis and for high throughput screening of molecules in search of antiproliferative effects specifically directed against the mutated KIT or against one or other of the intracellular molecules involved in signal transduction induced by mutant KIT.

Os mastócitos participam do sistema imunológico liberando mediadores farmacologicamente ativos. A principal via de ativação dos mastócitos é através do receptor de alta afinidade para a imunoglobulina E (FcRI). A ativação dos mastócitos via FcRI culmina com a liberação de mediadores. A enzima PLD atua sobre fosfolipídios hidrolisando a fosfatidilcolina em ácido fosfatídico e colina. A PLD é ativada após o estímulo via FcRI e possui um papel importante na transdução do sinal em mastócitos. Existem duas isoformas da enzima PLD, a PLD1 e a PLD2 que são expressas, diferentemente, de acordo com o tipo celular. Ambas as isoformas podem estar expressas numa mesma célula, apenas uma ou nenhuma. Neste estudo foram utilizadas células RBL-2H3 transfectadas para a super expressão PLD2 nas formas catalítica ativa (CA) e inativa (CI). O papel da PLD2 foi examinado nestas células com o objetivo de elucidar sua atuação no processo de secreção incluindo o aparelho de Golgi e os grânulos secretores. As células CA e CI possuem maior atividavidade de -hexosaminidase total, porém quando estimuladas mostram uma deficiência na liberação desta enzima, quando comparadas com as células selvagens. A PLD2 nas células CA, CI, VET e RBL-2H3 está localizada no citosol, sendo abundante na região justanuclear, principalmente nas células CI, sugerindo uma associação com o aparelho de Golgi. A dupla marcação com o mAb AA4, que imunomarca gangliosídeos derivados do GD1b da membrana plasmática e com anti-PLD2, mostrou que esta enzima não se localiza na membrana plasmática. A dupla marcação com anti-PLD2 e anti-GM130 mostrou que as áreas de maior concentração da PLD2 se co-localizam com o aparelho de Golgi, especialmente nas células CI. A marcação com anti-GM130 e os experimentos com microscopia eletrônica de transmissão mostraram que o aparelho de Golgi está organizado nas células CA e desorganizado nas células CI, onde se encontra disperso no citoplasma. Ainda, as células CI expressam menos GM130 em comparação com as demais linhagens celulares. Quando a produção de PA pela PLD está inibida pelo 1-Butanol, as células CA apresentam as mesmas características fenotípicas das células CI. A incubação das CI com PA resulta na reestruturação do aparelho de Golgi. A manutenção estrutural do aparelho de Golgi, também está relacionada com os microtúbulos. Nas células CI o centro organizador de microtúbulos é dificilmente identificado. Os microtúbulos nas células CI são desordenados em comparação com as demais linhagens celulares. Estes resultados mostram que a produção de PA pela PLD2 é importante na organização de microtúbulos e na manutenção da estrutura do aparelho de Golgi. As alterações celulares relacionadas com os microtúbulos e o aparelho de Golgi afetam o processo secretor nestas células e, provavelmente, em outros tipos de células secretoras. Estes achados poderão levar a novas estratégias terapêuticas para controlar a liberação de mediadores durante processos alérgicos e inflamatórios. / Mast cells are components of the immune system that liberate a wide variety of pharmacologically active mediators. The principle method of activating mast cells is through the high affinity receptor for IgE (FcRI). This activation then culminates with the release of mediators. Phospholipase D (PLD) acts on phospholipids, hydrolyzing phosphatidylcholine to phosphatidic acid (PA) and choline. PLD is activated following stimulation via FcRI and plays an important role in signal transduction in mast cells. PLD has two isoforms, PLD1 and PLD2, which are differentially expressed depending on the cell type where none, one or both may be expressed. RBL-2H3 cells, a mast cell line, transfected to super express catalytically active (CA) and inactive (CI) forms of PLD2 were used in the present study. The role of PLD2 was examined in these cells in order to clarify the action of PLD2 in the secretory process. Although the CA and CI cells posses a greater total -hexosaminidase activity, when stimulated these cells release less -hexosaminidase than cells transfected with empty vector or wild type RBL-2H3 cells. In all cell lines, PLD2 was dispersed throughout the cytoplasm with a concentration in the juxtanuclear region suggesting an association of PLD2 with the Golgi apparatus. Double labeling with anti-PLD2 and mAb AA4, which recognizes gangliosides derived from GD1b on the plasma membrane, showed that PLD2 was not associated with the plasma membrane. When the cells were double labeled with anti-PLD2 and anti-GM130, which labels the cis-Golgi saccules, PLD2 does colocalize with the Golgi apparatus, especially in CI cells. Labeling with anti-GM130 alone as well as experiments employing transmission electron microscopy revealed that the Golgi apparatus is well organized in the CA cells, but is disorganized and dispersed in the cytoplasm in the CI cells. By Western Blotting, the CI cells also expressed less GM130 than the other cell lines. When the production of PA by PLD2 was inhibited by 1-Butanol, the Golgi apparatus of the CA cells presented the same phenotypic characteristics as that of the CI cells. Conversely, incubation of the CI cells with PA resulted in the reorganization of the Golgi apparatus. The structural maintenance of the Golgi apparatus is also related to microtubules. In the CI cells, the microtubule organizing center was difficult to identify and the microtubules were disorganized in the cytoplasm as compared to the other cell lines. These results show that the production of PA by PLD2 is important in the arrangement of the microtubules and in maintaining the structure of the Golgi apparatus. Alterations in the distribution of the microtubules and the structure of the Golgi apparatus in the CI cells affect the secretory process in these cells, and such alterations may affect the secretory process in other cell types as well. The findings presented here may lead to new therapeutic strategies to control the production and release of mediators during allergic and inflammatory processes.

O mastocitoma é o tumor cutâneo mais comum dos cães, representando 7% a 21% dos tumores da pele e tecidos moles, 11% a 27% dos tumores malignos cutâneos nessa espécie. Eles possuem uma grande variedade de aparência e comportamento, o qual o torna um desafio seu tratamento. Os retinóides são uma promessa na luta contra o câncer. Entretanto, há poucos estudos sobre os efeitos dos retinóides em neoplasias caninas. O presente trabalho teve como objetivo caracterizar a cultura primária de mastocitomas caninos assim como investigar a quimiosensibilidade deste tumor ao ácido retinóico todo-trans (ATRA). A cultura primária de mastocitomas caninos foi realizada em co-cultivo com fibroblastos, que demonstrou uma interação favorável entre mastócitos e fibroblastos, com uma sobrevida média de 30 dias. A quimiosensibilidade dos mastocitomas caninos ao ATRA não mostrou diferenças entre os graus de mastocitomas, ou seja, tanto um mastocitoma grau II ou III respondem igualmente ao ATRA nas doses estudadas. Foi constatado também que o mastocitoma é mais sensível na concentração 10-4M de ATRA (p < 0,002). Existe também um efeito já nas primeiras 24h, mas esse não se altera em 48h, entretanto se intensifica após 72h. Podemos inferir, então, que a maior quimiosensibilidade de mastocitomas caninos ao ATRA se dá após 72h de exposição na dose de 10-4M. Podemos concluir que o ATRA apresenta efeitos sobre as células de mastocitomas caninos e pode ser usado como potencial adjuvante no tratamento desta neoplasia. / Mast cell tumor (MCT) is one of the most frequent neoplasms that affect the skin and soft tissue of the dog, representing about 7% a 21% of all skin tumors and 11% a 27% of malignant skin tumors in this specie. They present a great variety of appearance and behavior, which becomes a challenge to the treatment. The retinoids are well recognized as promising antitumor agents. However, there have only been a few reports about the effect of retinoids in canine cancers. The aim of this study was to characterize the primary mast cell tumor culture and to investigate the chemosensitivity of this tumor to all trans retinoic acid (ATRA). The primary cell culture of MCT was performed as co-cultive with fibroblasts, showing a positive interaction between mast cells and fibroblasts, with a lifetime of 30 days. The chemosensitivity of MCT to ATRA showed no difference between grade II or III, thus either a MCT grade II or grade III has the same response with ATRA at the doses studied. It has been shown that the MCT is more sensible at the dose 10-4M (p < 0,002). There is also an effect on first 24h untill 48h, changing after 72h. According to these results, it is possible to state that the great chemosensitivity of MCT to ATRA is after 72h of exposition at 10-4M. We can conclude that ATRA may be a potential adjunctive chemotherapeutic agent for the treatment of canine mast cell tumor.

Os mastócitos (MCs) estão presentes tanto no periodonto normal quanto inflamado, em diferentes quantidades e em vários locais. Nos últimos anos, a eficácia e a contribuição dos MCs em eliminar bactérias, através de sua atividade microbicida intracelular, estão se tornando cada vez mais reconhecidas. Assim, a partir de MCs murinos desafiados in vitro com o periodontopatógeno Aggregatibacter actinomycetemcomitans (ATCC 29523) por 3, 5, 10 e 24 horas, o presente estudo teve como objetivo investigar a capacidade microbicida intracelular de MCs, e comparar com a capacidade microbicida de macrófagos peritoneais murinos (MPs), considerados fagócitos profissionais, por meio da contagem das unidades formadoras de colônias. Além disso, avaliou-se a produção e liberação de mediadores microbicidas, óxido nítrico (NO) e peróxido de hidrogênio (H2O2), por meio do método colorimétrico de Griess e pela degradação de substratos fluorescentes, respectivamente. Para a análise estatística, foram utilizados os testes estatísticos ANOVA Fatorial seguido do teste de Tukey e teste de correlação de Pearson (p<0.05). Nossos resultados revelaram que os MCs foram capazes de eliminar eficientemente o periodontopatógeno, principalmente após 10h de desafio intracelular. Comparando-se a atividade microbicida dos dois tipos celulares, verificou-se, nos períodos de 3h e 5h de desafio, um menor percentual de colônias viáveis no interior de MPs, em comparação aos MCs. Inversamente, nos períodos de 10h e 24h, observaram-se menores valores percentuais de colônias intracelulares nos MCs em relação aos MPs. Além disso, a produção/liberação de NO bem como, em menor proporção, de H2O2 pelos MCs foram concordantes com a sua capacidade microbicida. Este é o primeiro estudo que demonstra a eficiente ação microbicida intracelular de MCs murinos contra Aggregatibacter actinomycetemcomitans, com produção e liberação de substâncias potencialmente bactericidas, e de forma mais eficaz que os macrófagos. Esses resultados sugerem a importância dessas células nos mecanismos de defesa presentes na doença periodontal induzida por placa dentobacteriana. / Mast cells (MCs) are present in both normal and inflamed periodontal tissues, in varying amounts and locations. Recently, MCs contribution in eliminating bacteria and its effectiveness, through its intracellular microbicidal activity, have been increasingly recognized. Thus, this study aimed to investigate the intracellular microbicide capacity of MCs, and compare it with the microbicide capacity of murine peritoneal macrophages (MPs), considered professional phagocytes, by counting the colony forming units. Both cell types were challenged in vitro with periodontopathogen Aggregatibacter actinomycetemcomitans (ATCC 29523) by 3, 5, 10 and 24 hours. Additionally, the production and release of microbicidal agents, nitric oxide (NO) and hydrogen peroxide (H2O2) were evaluated by means of colorimetric Griess method and by the degradation of fluorescent substrates, respectively. Statistical analysis was performed by ANOVA Factorial test followed by Tukey and Pearson\'s correlation test (p <0.05). Our results revealed that MCs are able to efficiently eliminate periodontopathogen, mainly after 10 hours of intracellular challenge. The microbicidal activity of both cell types, in 3 and 5 hours of challenge showed a lower percentage of viable colonies inside MPs, compared to MCs. Contradictorily, in 10 and 24 hours a lower percentage of intracellular colonies in MCs was observed in relation to MPs. Moreover, the production/release of NO and, in minor proportion, of H2O2 by MCs was in agreement with its microbicidal capacity. Therefore, this is the first report to describe the intracellular microicidal activity of murine MCs against Aggregatibacter actinomycetemcomitans, concerning production and release of potentially bactericidal substances, which is more effective than macrophages. These results suggest the importance of these cells in pathogenesis and defense mechanisms of biofilm-associated periodontal disease.