Les lymphomes T cutanés constituent un ensemble hétérogène de lymphomes non-hodkinniens. Les lymphomes T cutanés sont définis par une prolifération clonale de lymphocytes T malins et de cellules NK (natural killers) de localisation cutanée. Dans l'Union Européenne, l'indication du bexarotène par voie orale est le traitement des manifestations cutanées des lymphomes cutanés T épidermotropes (LCT), au stade avancé (ou dès un stade précoce aux États Unis). L'objectif de ce travail a été d'étudier les effets indésirables du bexarotène chez les patients atteints de lymphome cutané. Nous nous sommes plus particulièrement intéressés aux interactions du bexarotène avec le système de la coagulation et avec le métabolisme lipidique.Dans la première partie de nos travaux, nous avons étudié l'origine de la coagulopathie induite par le bexarotène. Nous avons montré que le bexarotène inhibe les facteurs IX et X de la coagulation, ce qui provoque le prolongement du temps de coagulation ; ces effets pourraient être à l'origine de la coagulopathie observée chez les patients traités au bexarotène.Dans la deuxième partie, nous avons montré que le bexarotène interagit également avec le métabolisme lipidique par l'activation du CETP et par l'inhibition de la lipoprotéine lipase, ce qui provoque une chlolésterémie et une triglyéridémie.Enfin, nous avons présenté les résultats préliminaires de l'essai clinique organisé au niveau de la région ouest de la France sur les effets indésirables du bexarotène.Les résultats de ce travail mettent en évidence l'importance de la structure chimique du bexarotène (effets de charges) dans la neutralisation des facteurs de coagulation d'une part et dans le mécanisme d'interaction avec le métabolisme lipidique (CETP et lipoprotéine lipase) d'autre part. La compréhension des mécanismes moléculaires conduisant à une coagulopathie et à la dyslipidémie représente un enjeu majeur pour prévenir la toxicité du bexarotène et pour permettre une meilleure prise en charge du patient. / The cutaneous T cell lymphomas are a heterogeneous group of non-lymphoma hodkinniens. The cutaneous T cell lymphomas are defined by a clonal proliferation of malignant T cells and NK (natural killer) cells from skin location. In the European Union, the indication of oral bexarotene is the treatment of cutaneous manifestations of cutaneous T-cell lymphomas epidermotropic (LCT) to advanced (or at an early stage in the United States). The objective of this work was to study the adverse effects of bexarotene in patients with cutaneous lymphoma. We are particularly interested in the interactions of bexarotene with the coagulation system and lipid metabolism.In the first part of our work, we studied the origin of the coagulopathy induced by bexarotene. We have shown that bexarotene inhibited factors IX and X of the coagulation causing the extension of clotting time and coagulopathy that was observed in bexarotene-treated patients. In a second part, we showed that Bexarotene induces in vitro cholesteryl ester transfer protein activity, and suppress lipoprotein lipase activity in human plasma.Finally, we presented the preliminary results of the clinical trial conducted at the western region of France on the adverse effects of bexarotene.The results of this study highlight the importance of the chemical structure of bexarotene (charge effects) in the neutralization of coagulation factors mechanisms on the one hand and in its interaction with lipid metabolism (CETP and lipoprotein lipase) on the other hand. Understanding the molecular mechanisms leading to coagulopathy and dyslipidemia is a major issue to prevent the toxicity of bexarotene and to elicit better management of the bexarotene-treated patient.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-27T15:30:53Z No. of bitstreams: 2 Dissertação - Halanna Cristina Barbosa Silva - 2016.pdf: 1692105 bytes, checksum: 1a6dba862cc9e4e590269d62f3d72bca (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-27T15:31:19Z (GMT) No. of bitstreams: 2 Dissertação - Halanna Cristina Barbosa Silva - 2016.pdf: 1692105 bytes, checksum: 1a6dba862cc9e4e590269d62f3d72bca (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-27T15:31:19Z (GMT). No. of bitstreams: 2 Dissertação - Halanna Cristina Barbosa Silva - 2016.pdf: 1692105 bytes, checksum: 1a6dba862cc9e4e590269d62f3d72bca (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-29 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Bexarotene is an agonist to retinoid X receptors (RXR) clinically used in cutaneous T cell lymphoma (CTCL). The oral bexaroteno therapy results in disagreeable side effects related to lipid metabolism, such that topical administration presents as an alternative to bexaroteno use increasing the drug concentration at the target site. Nanostructured systems, such as the deformable liposomes can be an interesting alternative to facilitate or promote increased cutaneous permeation of bexarotene. So, the aim of this study was the development and characterization of deformable bexarotene liposomes. Three surfactants were evaluated for composition of deformable liposomes (Span 80, Tween 80 and Span 85) in different concentrations (5, 10 and 15%). Liposomes were evaluated for average diameter, PdI and elasticity. And then a full factorial design with 3² triplicate central point was applied to analyze the influence of variables ethanol concentration and surfactant in the elasticity of the vesicles. A global solution was proposed by analyzing the Statistica 7.0 software applying the desirability tool and the deformable liposomes encapsulating bexarotene were prepared from the obtained response. Deformable liposomes were prepared by lipid film hydration and extrusion polycarbonate membrane (200 and 100 nm). The desirability function provided a global solution with 5.25% (v / v) ethanol and 5% (w / v) Span 80. Deformable liposomes had encapsulation efficiency of 99.67±3.4%, diameter average of 93.69±1.95 nm and PDI 0.092±0.02. Lyophilized liposomes showed higher elasticity parameters than non-lyophilized formulations, with elasticity up to 215.5±5.5 (mg.s-1.cm-2) for formulations with sucrose and 22.13±1.04 (mg. s-1.cm-2) for conventional liposomes. EPR studies demonstrated that lyophilized formulations presented higher molecular dynamics of lipids regarding the non lyophilized in all formulations, while the formulations without BXT was most dynamic in formulations in which sucrose was used as cryoprotectant, in formulations with BXT occurs the oposite. In vitro skin permeation studies, BXT deformable liposomes had a penetration rate EC about 5 times greater than the conventional liposomes. Thus, the developed deformable liposomes present as bexarotene the potential permeation enhancer on the skin. / O bexaroteno é um agonista dos receptores retinoides X (RXR) clinicamente utilizado no tratamento de linfoma cutâneo de células T (LCCT). A terapia oral do bexaroteno resulta em efeitos colaterais desagradáveis relacionados ao metabolismo de lipídios, de forma que a via tópica se apresenta como alternativa para administração do bexaroteno, aumentando a concentração de fármaco no sítio alvo. O uso de sistemas nanoestruturados, como por exemplo, os lipossomas deformáveis, pode ser uma alternativa interessante para facilitar ou promover maior permeação cutânea do bexaroteno. Assim, o objetivo deste trabalho foi o desenvolvimento e caracterização de lipossomas deformáveis de bexaroteno. Para selecionar os componentes da formulação foram avaliados três tensoativos (Span 80, Tween 80 e Span 85) em três concentrações diferentes (5, 10 e 15%). Os lipossomas foram avaliados quanto ao diâmetro médio, PdI e elasticidade. A seguir um planejamento fatorial completo 3² com triplicata do ponto central foi aplicado para analisar a influência das variáveis de concentração do etanol e do tensoativo na elasticidade das vesículas. Uma solução global foi proposta mediante análise pelo software Statistica 7.0 aplicando-se a ferramenta desejabilidade e, os lipossomas deformáveis encapsulando bexaroteno foram preparados a partir da resposta obtida. Lipossomas deformáveis foram preparados por hidratação do filme lipídico e extrusão em membrana de policarbonato (200 e 100 nm). A função desejabilidade ofereceu uma solução global com 5,25% (v/v) de etanol e 5% (p/v) de Span 80. Os lipossomas deformáveis obtidos apresentaram eficiência de encapsulação de 99,67±3,4 %, diâmetro médio de 93,69±1,95 nm e PdI 0,092±0,02. Os lipossomas liofilizados indicaram parâmetros de elasticidade superiores as formulações não liofilizadas, com elasticidade de até 215,5±5,5 (mg.s-1.cm-2) para formulações com sacarose e 22,13±1,04 (mg.s-1.cm-2) para lipossomas convencionais. Os estudos de RPE demonstraram que as formulações liofilizadas apresentaram maior dinâmica molecular dos lipídios em relação as não liofilizadas em todas as formulações, enquanto nas formulações sem BXT houve maior dinâmica nas formulações em que a sacarose foi utilizada como crioprotetor, nas formulações com BXT ocorre o contrário. Nos estudos de permeação cutânea in vitro, os lipossomas deformáveis de BXT tiveram uma taxa de penetração no EC cerca de 5 vezes superior aos lipossomas convencionais. Dessa forma, os lipossomas deformáveis desenvolvidos se apresentam como potencial promotor de permeação do bexaroteno na pele.