Made available in DSpace on 2014-12-17T15:32:28Z (GMT). No. of bitstreams: 1 JanainaCL.pdf: 1946389 bytes, checksum: 9edf9a3e8f8e033293bf82a3b2344d4d (MD5) Previous issue date: 2009-02-28 / Host response plays a major role in the pathogenesis of periodontal disease. Mediators such as inflammatory cytokines which are secreted during the immune response to bacterial challenges have ambiguous functions that may or may not lead to protection of the attacked tissue. In this context, experimental evidence suggests that T-helper 1 (Th-1) and T-helper 2 (Th-2) mediated responses are potentially important during the disease process. The aims of this study therefore were to further clarify the role played by Th2 cells during different time points of the active phase of periodontal disease, as well as, to investigate whether there was any evidence of a Th1 response in the periodontal disease microenvironment. Experimental periodontitis was induced in 30 Wistar male rats by placing cotton ligatures around the mandibular first molars. The rats were then randomly divided into two groups. Group1 (G1=15) and Group 2 (G2=15). In G1 the ligatures were maintained for 2 days, whereas in G2 the ligatures were left for 15 days, a time point that corresponds to the advanced stage of periodontal disease The contra-lateral teeth served as controls (no ligatures). Immunohistochemical investigation for the presence in gingival tissue of Th2 specific transcription factor (GATA3) and the subunit of the IFN-γ receptor was carried out after the disease induction period. Light microscopy analysis revealed a decrease in the expression of GATA-3 as bone loss progressed. On the other hand, although IFN-γ R1 was detected at an early stage of the active phase of disease its expression remained unaltered during the remaining period of the study. These results indicate that the Th2 response have a protective role during the pathogenesis of periodontal disease and that the progression of the periodontal disease is related with the unbalance of the responses Th1/Th2 / A resposta do hospedeiro tem um importante papel na patog?nese da doen?a periodontal. Mediadores como as citocinas liberadas por c?lulas inflamat?rias durante a resposta imune, frente a um ataque bacteriano, desempenham pap?is antag?nicos que podem culminar com a prote??o ou n?o do tecido agredido, o que fundamenta o paradigma da resposta Th1/Th2 na doen?a periodontal. Na tentativa de esclarecer a participa??o das c?lulas Th2, em diferentes tempos, na fase ativa da doen?a periodontal, bem como observar se o microambiente encontrava-se preparado para uma resposta Th1, induziu-se doen?a periodontal experimental em 30 ratos Wistar machos, atrav?s da coloca??o de ligaduras de algod?o ao redor dos primeiros molares mandibulares. Os animais foram divididos, aleatoriamente, em dois grupos: Grupo 1 (G1 = 15) e Grupo 2 (G2 = 15). Em G1 as ligaduras foram mantidas por 2 dias, que configurou o est?gio inicial da doen?a periodontal e no G2, as ligaduras foram mantidas por 15 dias, que foi considerado o est?gio avan?ado da doen?a periodontal. Os dentes contralaterais serviram de controle (sem ligaduras). Avalia??o imuno-histoqu?mica para o fator de transcri??o espec?fico para c?lula Th2 (GATA-3) e da subunidade IFN- γ R1 do receptor para IFN-γ (principal citocina da resposta Th1) foram avaliados nos tecidos gengivais dos ratos ap?s o per?odo de indu??o da doen?a. Ap?s an?lise microsc?pica observamos que o fator de transcri??o GATA-3 teve sua express?o diminu?da com o avan?o da perda ?ssea induzida e a subunidade IFN-γ R1 passou a se expressar na fase ativa da doen?a experimental, contudo n?o se alterou com a progress?o da destrui??o tecidual. Estes resultados indicam que a resposta Th2 pode estar associada a uma resposta protetora na patog?nese da doen?a periodontal e que a progress?o da doen?a periodontal est? relacionada com o desequil?brio das respostas Th1/Th2