Orientador: Alvimar Lima de Castro / Banca: Renata Tucci / Banca: José Fernando Garcia / Banca: Sérgio Roberto Peres Line / Banca: José Américo de Oliveira / Resumo: INTRODUÇÃO: As alterações em gengiva induzidas por medicamentos têm sido pouco estudadas quanto à expressão in vivo dos genes das metoloproteinases (MMPs). O objetivo do presente trabalho foi avaliar o padrão histológico de distribuição de fibras colágenas após a administração de ciclosporina, nifedipina ou fenitoína e correlacionar com a expressão dos genes do colágeno do tipo I, MMP-1 e MMP2. MATERIAL E MÉTODO: Amostras da gengiva da área de canino superior direito foram obtidas de doze macacos prego (Cebus apella) machos. A extremidade mesial de cada amostra foi imediatamente congelada em nitrogênio líquido enquanto que a distal foi processada para inclusão em parafina. Após uma semana, os animais foram divididos em três grupos que receberam doses diárias de ciclosporina, fenitoína ou nifedipina, durante 120 dias. Procedeu-se à remoção de amostras da gengiva da área do canino superior esquerdo de dois animais de cada grupo aos 52 e 120 dias. Os cortes histológicos foram corados pelas técnicas da hematoxilina e eosina, vermelho picrosirius, além da marcação imunoistoquímica para colágeno do tipo IV. O RT-PCR semiquantitativo foi realizado para se determinar os níveis de mRNA. RESULTADOS: No grupo controle, houve o predomínio de fibras colágenas maduras, evidenciadas com a cor vermelha em cortes corados pela técnica do vermelho picrosirius analisados com microscópio de luz polarizada. Observou-se nos grupos tratados aos 52 e 120 dias um aumento da porcentagem de áreas ocupadas por fibras imaturas, em todos os grupos, independentemente da idade do animal. No entanto, não foram observadas diferenças morfológicas entre os grupos controle e tratado nos cortes corados pela hematoxilina e eosina. Houve uma tendência a valores médios mais baixos ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Background: Few studies have focused on the in vivo expression of matrix metalloproteinase (MMP) genes in gingival changes induced by drugs. The aim of the present study was to evaluate the histological pattern of collagen fiber distribution after phenytoin, cyclosporine or nifedipine medication and correlate with collagen type 1, MMP-1 and MMP-2 gene expression levels. Methods: Gingival samples were obtained from superior right canine area of twelve male capuchin monkeys (Cebus apella). The mesial part of the biopsy specimens was immediately frozen in liquid nitrogen, while the distal one was processed for paraffin inclusion. One week after the control biopsy, the animals were divided in three groups that received daily doses of cyclosporine, phenytoin or nifedipine during 120 days. Gingival samples were obtained from left superior canine area on 52nd and 120th day of treatment (two animal of each experimental group). Histologic sections were subjected to hematoxylin and eosin, picrosirius red stainings, and to immunohistochemical reaction for collagen type IV. MMP-1, MMP-2 and collagen type I mRNA levels were determined by RT-PCR. Results: Predominance of mature collagen fibers was observed in the control group after picrosirius red staining, visualized as red fibers under polarized microscope. Increased percentage of areas occupied by immature collagen fibers was observed on 52 and 120 experimental periods, in all groups, despite the animal age. However, no morphological differences between treated and control groups were observed on hematoxilin and eosin stained sections. There was a trend to lower levels of MMP-1 expression on 52-day samples. However, MMP-2 and collagen type I gene expressions seemed to be phased and drug-related. Conclusions: The results allowed the ...(Complete abstract click electronic access below) / Doutor

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L’arthrose (OA) est la maladie articulaire la plus répandue dans le monde faisant l’objet de nombreux travaux de recherche en raison de son lourd impact socioéconomique. Plusieurs travaux dans ce domaine ont pour objectif de déterminer les mécanismes moléculaires impliqués dans sa physiopathologie. Plusieurs travaux ont appuyés l’implication de la prostaglandine (E2) PGE2 dans sa physiopathologie, contrairement à la prostaglandine (D2) (PGD2) dont le rôle reste à déterminer. C’est pourquoi, nous nous sommes penchés dans cette thèse à l’étude de cette dernière molécule. Dans la première partie de nos travaux, nous avons montré que la PGD2 diminue au niveau du cartilage articulaire et au niveau niveau des explants de cartilage humains, la production des métalloprotéases-1(MMP-1) et MMP-13 induites par (Interleukine-1β) l’IL-1β. Cette diminution de la production protéique est accompagnée d’une diminution de l’expression au niveau de l’ARNm, et d’une diminution de l’activité du promoteur de MMP-1 et MMP-13. Cet effet est exercé via le récepteur D prostanoïde (DP1), bien que le Chemoattractant receptor expressed on Th2 cells (CRTH2) soit également exprimé chez les chondrocytes humains, mais ne semble pas être impliqué dans l’effet observé. Cette action inhibitrice se fait via la voie DP1/AMPc/protéine kinase A (AMPc/PKA). Dans la suite de nos travaux, nous avons montré pour la première fois l’expression des prostaglandines D-synthases responsables de la biosynthèse de la PGD2 au niveau des chondrocytes humains par immunohistochimie, avec des niveaux d’expression de l’ARNm plus élevés de la L-PGDS au niveau du cartilage OA comparativement au cartilage normal. L’IL-1β pourrait être responsable de cette augmentation via l’activation de la voie JNK et p38 MAPK, ainsi que par la voie NF-κB. L’ensemble de ces données indiquent que la modulation des niveaux de la PGD2 au niveau de l’articulation pourrait être pourvue d’un important potentiel thérapeutique. La L-PGDS pour sa part semble avoir un rôle important dans la physiopathologie de l’OA. / Osteoarthritis (OA) is the most common joint disease world wide, because of its higher socioeconomic impact it is one of the most studied joint diseases. The aims of these studies was to determine the molecular mechanisms involved in the pathophysiology of osteaarthritis. Previous studies have mainly focused on the involvement of prostaglandin (E2) PGE2 in contrast to PGD2 in the pathogenesis osteoarthritis as such the role of PGD2 remains unclear. In this thesis we examined the involvment of PGD2 in the pathogenesis of OA. In the first part of our work, we showed that in a dose dependent manner PGD2 decreased the interleukin-1β (IL-1β)–induced mettalloproteases (MMP-1) and MMP-13 expression both at protein and mRNA levels by supression of their promoter activity. The inhibitory effect was exerted via the D prostanoid receptor (DP1) and mediated through the cAMP/protein kinase A (PKA) signalling pathway. Although human chondrocytes do express the Chemoattractant Receptor Expressed on Th2 cells (CRTH2) the latter were not implicated in the inhibiton of MMP-1 and MMP-13. In the second part of our work, we showed the expression of prostaglandin D synthases (PGDS) responsible for the biosynthesis of PGD2 in human chondrocytes, with higher levels of mRNA expression of lipocaline type prostaglandin D-synthase (L-PGDS) in OA cartilage compared to normal cartilage. IL-1β may be responsible for this increase via the activation of Jun N-terminal kinase (JNK) and p38 mitogen activated protein kinase (MAPK), as well as the nuclear factor-κB (NF-κB). Together, these data indicate that modulation of the levels of PGD2 at the joint may be provided with an important therapeutic potential. L-PGDS in turn seems to have an important role in the pathogenesis of OA.