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Doctoral Thesis
DOI
10.11606/T.5.2008.tde-25032009-101503
Document
Author
Full name
Daher Cezar Chade
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Srougi, Miguel (President)
Gattas, Gilka Jorge Figaro
Leite, Luciana Cezar de Cerqueira
Nesrallah, Luciano Joao
Ortiz, Valdemar
Title in Portuguese
Avaliação do bacilo de Calmette-Guérin recombinante expressando o antígeno S1PT no tratamento do carcinoma urotelial de bexiga em modelo experimental
Keywords in Portuguese
Administração intravesical
Imunoterapia
Mycobacterium bovis
Neoplasias da bexiga urinária
Vacinas anti-câncer
Abstract in Portuguese
Introdução: A imunoterapia intravesical com o bacilo de Calmette-Guérin (BCG) é o tratamento adjuvante de escolha no câncer superficial de bexiga. Recentemente, os estudos do mecanismo imunoterápico do BCG têm permitido identificar as reações imunológicas e os genes associados ao efeito antitumoral, possibilitando a produção de vacinas recombinantes, possivelmente mais efetivas e com menos efeitos colaterais. Com esses objetivos, associou-se o componente pertussis (S1PT) ao BCG, criando uma variante recombinante (rBCG-S1PT) com capacidade para promover uma resposta imune direcionada ao tipo T helper 1 (Th1), o que poderá elevar a eficácia antitumoral do imunoterápico. Objetivo: Avaliar comparativamente o efeito antitumoral do rBCG-S1PT e do BCG no modelo experimental de carcinoma urotelial de bexiga. Métodos: O estabelecimento do modelo murino ortotópico e singênico de tumor vesical foi realizado através da implantação transuretral das células tumorais de bexiga da linhagem MB49 de camundongo C57BL/6. Experimento I Os animais (modelo experimental) foram divididos em três grupos, os quais receberam 4 aplicações semanais de rBCG-S1PT, BCG, ou soro fisiológico (grupo controle), por via intravesical. Após 7 dias da última aplicação, foram extraídos o baço e a bexiga, com o intuito de inferir o peso tumoral. Em seguida, as bexigas foram submetidas à avaliação do padrão de resposta imunológica e exame anátomo-patológico e imunohistoquímico. Experimento II Realizado como descrito no Experimento I, porém os animais foram acompanhados por 60 dias para análise de sobrevida. Experimento III Este ensaio foi realizado como descrito anteriormente, porém não foi realizada a implantação tumoral, para controle dos achados imunológicos e anátomo-patológicos. Resultados: A taxa média de implantação tumoral foi de aproximadamente 90% dos animais inoculados. Obtivemos redução das médias dos pesos vesicais dos grupos BCG e rBCG-S1PT (p<0,001). Nos dois grupos tratados com os imunoterápicos observou-se aumento significativo da expressão de TNF-, a qual foi mais intensa com o uso do rBCGS1PT (p<0,05). A IL-10 também teve aumento significante de sua expressão no grupo BCG recombinante (p<0,01). Os esplenócitos provenientes dos camundongos que foram tratados com imunoterápicos diminuíram a viabilidade das células tumorais MB49, sendo que este efeito foi mais intenso no grupo rBCG-S1PT. O grupo de animais tratados com rBCG-S1PT apresentou aumento significativo da sobrevida em relação aos outros grupos (Experimento II). As aplicações dos imunoterápicos em animais sem tumor (experimento III) não revelaram diferenças histológicas em relação ao grupo controle e o padrão de resposta imunológica encontrado sugere uma tendência à resposta Th1. Conclusão: Obtivemos sucesso no estabelecimento do modelo murino ortotópico singênico de tumor vesical. O imunoterápico rBCG-S1PT apresentou mais benefícios no tratamento do tumor vesical ortotópico em camundongos em relação ao BCG, como também maior redução da viabilidade das células tumorais in vitro. A cepa rBCG-S1PT apresentou elevação significativamente maior das citocinas da resposta imune Th1 em relação aos demais grupos. Concluimos, então, que os dados apresentados sugerem a possibilidade deste recombinante proporcionar melhor controle clínico do tumor vesical em humanos que a imunoterapia com BCG
Title in English
Evaluation of recombinant bacillus Calmette-Guérin expressing S1PT in the treatment of urothelial bladder carcinoma in an experimental model
Keywords in English
Administration intravesical
Cancer vaccines
Immunotherapy
Mycobacterium bovis
Urinary bladder neoplasms
Abstract in English
Introduction: The intravesical immunotherapy with bacillus Calmette-Guérin (BCG) is the adjuvant treatment of choice in superficial bladder cancer. Recently, studies of the mechanism of BCG have identified the immune reactions favorable and the genes responsible for the antitumor effect, enabling the production of recombinant vaccines, possibly more effective and with fewer side effects. With those goals, the pertussis toxin (S1PT) was combined to BCG, creating a recombinant variant (rBCG-S1PT) with the capacity to promote an immune response targeted to the T helper type 1 (Th1), which may increase the effectiveness of its antitumor effect. Objective: Compare the antitumor effects of rBCG-S1PT and BCG in an experimental model of bladder cancer. Methods: The development of the animal model of bladder cancer was conducted by transurethral instillation of bladder tumor cell line MB49 of the mouse strain C57BL/6, setting the orthotopic and syngeneic murine model. Experiment I - The animal models were divided into three groups, which received 4 weekly intravesical applications of rBCG-S1PT, BCG, or saline (SF - control group). After 7 days of the last instillation, splenectomy was performed for splenocyte culture and the bladders extracted and weighed in order to infer the tumor weight. Then, the bladders were divided into two pieces. The first was used for molecular analysis to assess the pattern of immune response. The second was sent to histopathological analysis. Experiment II - Held as described in Experiment I, but the animals were monitored for 60 days for analysis of survival. Experiment III - This test was carried out as previously described (Experiment I), but with no tumor cells instillation. Results: The rate of tumor implantation was 90% of the animals submitted to tumor inoculation. We obtained reduction of the average weights of bladder in groups BCG and rBCG-S1PT ((p<0,001). In both groups treated with immunotherapy, there was an increase of expression of interleukins TNF-, which was more intense in the group treated with rBCG-S1PT (p<0,05). There was also increased expression of IL-10 in the recombinant BCG (p<0,01). The splenocytes from animals that received immunotherapies had reduced tumor cells viability, more intensely demonstrated in the rBCG-S1PT group. The analysis of survival showed a significant increase in the group of animals treated with rBCGS1PT (Experiment II). The instillation of immunotherapeutic agents in animals without tumor did not demonstrate histological differences when compared to the control group and the immunological response pattern was similar to that of Experiment I (Experiment III). Conclusion: The establishment of the syngeneic orthotopic animal model was successful. The immunotherapy with rBCG-S1PT demonstrated more benefits than BCG in the treatment of bladder cancer in mice, reducing the bladder weight, increasing survival, and reducing tumor cells viability in vitro. The immune response obtained with the rBCG-S1PT expressed higher cytokines related to Th1. All this data may indicate that this recombinant agent may promote better bladder tumor control than BCG imunotherapy
 
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Publishing Date
2009-04-06
 
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