Thesis (M.Sc.). / Written for the Division of Experimental Medicine. Title from title page of PDF (viewed 2008/12/04). Includes bibliographical references.

Thesis (Ph. D.)--School of Dentistry. University of Missouri--Kansas City, 2003. / "A dissertation in oral biology and molecular biology and biochemistry." Advisor: Jian Q. Feng. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed July 16, 2008. Includes bibliographical references (leaves 109-121). Online version of the print edition.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed on July 19, 2010). Includes bibliographical references.

Submitted by JONLENO COUTINHO PAIVA PITOMBO null (jomtombo@hotmail.com) on 2016-05-23T15:01:17Z No. of bitstreams: 1 Jonleno Coutinho P Pitombo.pdf: 2907326 bytes, checksum: b153a02592cf15ac920e757f91e472b8 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-25T16:58:23Z (GMT) No. of bitstreams: 1 pitombo_jcp_me_arafo.pdf: 2907326 bytes, checksum: b153a02592cf15ac920e757f91e472b8 (MD5) / Made available in DSpace on 2016-05-25T16:58:23Z (GMT). No. of bitstreams: 1 pitombo_jcp_me_arafo.pdf: 2907326 bytes, checksum: b153a02592cf15ac920e757f91e472b8 (MD5) Previous issue date: 2016-03-21 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os mecanismos de ação dos andrógenos sobre homeostase e regulação das células que participam do turnover ósseo em fêmeas ainda são pouco compreendidos. Este trabalho teve como principal objetivo avaliar a participação de andrógenos na diferenciação e atividade de osteoclastos in vitro. Células totais de medula óssea de fêmur e tíbia de camundongos fêmeas foram utilizadas como fonte de células precursoras de osteoclastos, sendo cultivadas utilizando-se α-MEM suplementado e em presença de RANK-L (30ng/mL) e M-CSF (50ng/mL). As células foram tratadas com testosterona (T) diidrotestosterona (DHT) e antagonistas de receptores de hormônios sexuais, como flutamida (FLU) e fulvestranto (FUL). O anastrozol (ANA) foi usado para inibição da enzima aromatase e o etanol (0,01%) foi utilizado como controle. Após cinco dias, as células foram fixadas, coradas com TRAP e contadas, considerando-se células TRAP-positivas com 3 ou mais núcleos. Para o ensaio de atividade, foram utilizadas placas revestidas com fosfato de cálcio inorgânico e a área de reabsorção foi calculada com o auxílio de software. O estágio de diferenciação osteoclástica foi avaliado por RT-qPCR e a modulação da expressão de receptores para hormônios sexuais foi avaliada por Western Blot. Os andrógenos (T e DHT) não exerceram efeitos sobre a diferenciação e atividade de osteoclastos (ANOVA; p>0,05). Por outro lado, os tratamentos com ANA, FLU e FUL, associados ou não a T, regularam positivamente a diferenciação e atividade de osteoclastos. A expressão gênica de RANK, Catepsina K, NFATc1 e β3 integrina não foi alterada pelos tratamentos propostos (ANOVA; p>0,05). Além disso, os tratamentos com T, DHT, FLU e FUL modularam a expressão proteica do receptor de andrógeno (AR) e dos receptores de estrógeno (ERα e ERβ) por Western Blot. Tomados em conjunto, nossos resultados indicam que os andrógenos exercem limitada participação na diferenciação e atividade de osteoclastos de camundongos fêmeas e que este processo é mediado, ao menos em parte, por ações indiretas da T e pela modulação de receptores de hormônios sexuais. / The action mechanisms of androgens on homeostasis and the regulation of cells that participate in bone turnover in females are still poorly understood. This study had as main objective to evaluate the participation of androgens in the differentiation and activity of in vitro osteoclasts. Total bone marrow cells from femur and tibia of female mice were used as a source of precursor cells of osteoclasts, they were cultivated using supplemented α-MEM and in the presence of RANK-L (30ng/mL) and M-CSF (50ng/mL). The cells were treated with testosterone (T), dihydrotestosterone (DHT) and antagonists of sexual hormone receptors such as flutamide (FLU) and fulvestrant (FUL). Anastrozole (ANA) was used for inhibiting the aromatase enzyme and ethanol (0.01%) was used as a control. After five days, the cells were fixed, colored with TRAP and counted, considering TRAP-positive cells those ones containing 3 or more nuclei. For the activity assay, were used plaques covered with inorganic calcium phosphate and the area of reabsorption was calculated with the assistance of a software. The osteoclast differentiation stage was evaluated by RT-qPCR and the modulation of the expression of receptors for sexual hormones was assessed by Western Blotting. The androgens (T and DHT) did not exert effects in differentiation and activity of osteoclasts (ANOVA, p> 0.05). On the other hand, the treatments with ANA, FLU and FUL, associated or not to T, positively regulated the differentiation and activity of osteoclasts. The genic expression of RANK, Cathepsin K, NFATc1 and β3 integrin was not altered by the proposed treatments (ANOVA, p> 0.05). Moreover, the treatments with T, DHT, FLU and FUL modulated the protein expression of the androgen receptor (AR) and of the estrogen receptors (ERα and ERβ) by Western Blotting. Taken together, our results indicate that the androgens exert limited participation in differentiation and activity of osteoclasts of female mice and that this process is mediated, at least in part, by indirect actions of T and by the modulation of sexual hormone receptors. / CNPq: 133815/2014-5 / FAPESP: 2013/12014-6

A doença periodontal é a doença crônica mais prevalente nas doenças orais. Dentre os mediadores desse processo contam-se a Resolvina E1 (RvE1), um mediador pró-resolução da inflamação capaz de diminuir a perda óssea secundária á doença periodontal em coelhos, e o oxido nítrico (NO), o qual pode ser produzido em grandes quantidades pela ação de citocinas e estimular a diferenciação e atividade osteoclástica. O objetivo deste estudo foi investigar os efeitos da RvE1 em osteoclastos (OCs) em cultura e os mecanismos envolvidos, bem como o papel do NO na progressão da periodontite experimental em ratos e as alterações sistémicas resultantes de danos oxidativos. A diferenciação de OCs foi induzida em células de medula óssea de camundongos C57BL/6 em cultura (7 dias) e tratadas com diferentes doses de RvE1. NFkB e Akt fosforilada foram analisadas por Western blotting e a expressão gênica de NO sintase (NOS) induzível (iNOS) por \"real-time\" PCR. A participação dos receptores ChemR23 e BLT-1 na resposta à RvE1 foi estudada em membranas isoladas de OCs empregando radioligantes. A perda óssea alveolar e danos em órgãos periféricos foram analisados em ratos com periodontite induzida por ligadura (P) e sob tratamento de longo prazo com o inibidor não-seletivo de NOS, L-NAME. Os animais receberam L-NAME durante as 2 semanas prévias à indução da periodontite e até o momento do sacrifício (3, 7 ou 14 após a ligadura). A perda óssea alveolar foi avaliada radiograficamente, e análises do conteúdo de proteínas contendo nitrotirosina (NT), espécies reativas do ácido tiobarbitúrico (TBARs) e atividade da mieloperoxidase (MPO) foram realisadas em amostras de coração, baço, rim, fígado e pulmão. RvE1 (3 ng/mL) através da ativação do receptor para BLT-1 (mas não ChemR23) inibiu a diferenciação e atividade de OCs (p<0,05) após 5 ou 7 dias de cultura, assim como a fosforilação dos dois sítios da Akt e a traslocação do NF-<font face=\"symbol\">kB para o núcleo, um evento chave tanto na diferenciação de OCs (p<0,05) como na diminuição da expressão de iNOS. In vivo, ratos P (dia 7) mostraram um aumento na expressão de NT cardíaca e MPO renal em comparação ao grupo Sham (S; p<0,05). L-NAME resultou em aumento de NT hepática no grupo P no dia 3 (p<0,05), mas diminuição da NT cardíaca no dia 7 (p<0,01). Em comparação ao grupo P, ratos P+LN mostraram um aumento significativo na MPO hepática, cardíaca e renal no dia 3 (p<0,05), mas diminuição de MPO (dia 7) e TBARs esplênico (dia 3, p<0,05). Em resumo, mostramos que a RvE1 ligando-se ao receptor para BLT-1 inibe a diferenciação e atividade de OCs interferindo com a sinalização de Akt e NF-<font face=\"symbol\">kB, e consequentemente inibindo a expressão da iNOS, e que o NO tem um papel central na periodontite, não só relacionado a consequências locais na perda óssea alveolar, como também em órgãos periféricos distantes. / The periodontal disease is the most prevalent chronic disease in oral diseases. Among the mediators of this process, is the Resolvin E1 (RvE1), a novel mediator pro-resolving of inflammation that is capable to decrease alveolar bone loss secondary to periodontal disease in rabbits; and the nitric oxide (NO), that can be produced in large amount, induced by cytokines and it can stimulate the osteoclast differentiation and activity. The aim of this study is to investigate the effects of RvE1 on osteoclasts (OCs) culture and the pathway involved, also the role of NO in the progression of experimental periodontitis in rats and systemic alterations due to oxidative damage. The OCs differentiation was induced in bone marrow cell culture from C57BL/6 mice (7 days) and treated with various doses of RvE1. NF<font face=\"symbol\">kB and Akt phosphorylation were analyzed with Western blotting and the genic expression of NO synthase (NOS) inducible (iNOS) with \"Real Time\" PCR. The role of receptors ChemR23 and BLT-1 was accessed in OCs isolated membranes performing radioligants. The alveolar bone loss and peripheral organ damage was assessed in rats with ligature-induced periodontitis (P) under a long-term treatment of a NOS inhibitor, L-NAME. The animals received L-NAME from two weeks prior to periodontitis induction and until their sacrifice (3, 7 and 14 days after ligature). The alveolar bone loss was evaluated radiographically, and the protein nitrotyrosine (NT) content, reactive species of thiobarbituric acid (TBARs) and myeloperoxidase activity (MPO) were analyzed in samples of heart, spleen, kidney, lungs and kidneys. RvE1 (3 ng/mL) trough BLT-1 receptor activation (but not ChemR23) inhibits the OCs differentiation and activity (p<0.05) after 5 or 7 days of the culture, as well as the Akt phosphorylation and NF-<font face=\"symbol\">kB translocation to the nucleus, a key event both in OCs differentiation (p<0.05) and iNOS expression decreases. In vivo, P rats (day 7) show an increase of heart NT and renal MPO, but lower lung MPO activity in comparison to the Sham group (S; p<0.05). L-NAME leads to an increase the liver NT expression in P rats on day 3 (p<0.05), but decreases the cardiac NT on day 7 (p<0.01). In comparison with the P group, P+LN rats showed significantly increased liver, heart and kidney MPO content on day 3 (p<0.05), but lower lung MPO (day 7) and spleen TBARs (day 3) content (p<0.05). In summary we have shown that RvE1 binding on BLT-1 receptor inhibits OCs differentiation and activity by interfering with Akt and NF-<font face=\"symbol\">kB signaling and consequently iNOS inhibition, and NO has a central role on periodontitis, not only related to the local consequences on alveolar bone resorption, but also on distant peripheral organs.

Orientadores: Enilson Antônio Sallum, João Baptista César Neto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-16T09:18:22Z (GMT). No. of bitstreams: 1 Cayana_EzymarGomes_D.pdf: 2999544 bytes, checksum: 87318d3714c0dada68775562aa703c38 (MD5) Previous issue date: 2010 / Resumo: O objetivo deste estudo foi investigar histológica e histoquimicamente a influência da inalação da fumaça de cigarros (IFC) e da administração intermitente de PTH 1-34 sobre a perda óssea alveolar na região de furca em ratas submetidas a periodontite experimental induzida por meio de ligaduras. Animais foram aleatoriamente distribuídos nos grupos: 1 - placebo (veículo) controle (n=11); 2- IFC + placebo (n=15); 3- PTH 1-34 (n=10); 4 - IFC + PTH 1-34 (n=15). Dentes controlaterais, não receberam ligaduras e serviram como controle. Após 60 dias com ligaduras, os animais foram sacrificados. A avaliação histométrica foi realizada quantificando a área de perda óssea na região da bifurcação e a análise histoquímica por meio de reação de fosfatase ácida tártarato resistente (TRAP). Os dados coletados foram analisados estatisticamente utilizando a análise de variância ANOVA e o teste Tukey (=5%). Nos dentes com ligaduras, uma análise intergrupo revelou aumento estatisticamente significante da perda óssea como resultado do modelo de periodontite induzida quando o grupo 2 foi comparado com os grupos 1, 3 e 4 respectivamente (p<0,05). O número de células marcadas positivamente pelo TRAP na superfície linear da crista óssea demonstrou um aumento significativo no número de osteoclastos para o grupo 2 quando comparado com os grupos 1, 3 e 4, respectivamente (P<0,05). Dentro dos limites do presente estudo, pode-se concluir que o PTH 1-34 na ausência ou presença de IFC pode reduzir significativamente a perda óssea resultante da periodontite experimental induzida por ligaduras / Abstract: The aim of the present investigation was to histologically and histoquimically evaluate, in an animal model (rats), the influence of cigarette smoke inhalation (CSI) and intermittent administration of PTH in rodents would block the alveolar bone loss when a ligature-induced periodontitis is used. Animals were randomly assigned in groups: 1 - placebo (vehicle) Control-ligated (n=11); 2 - CSI + placebo- ligated (n=15); 3 - PTH-treated ligated (n=10); 4 - CSI + PTH-treated ligated (n=15). Contralateral teeth were unligated to serve as controls. After 60 days with ligatures, the animals were killed. The histometric avaluete determined the area between the bone crest and cementum surface in the furcation regions of teeth and the number of cells positive for tartrate-resistant acid phosphatase (TRAP). The date were statistically analysed using ANOVA and Tukey's test (alpha=5%). At the ligated sites, intergroup analysis revealed significantly increased the bone loss resulting from ligature-induced periodontitis when group 2 compared with group 1, 3 and 4, respectively (P<0,05). The number of TRAP-Positive cell in the linear surface of the bone crest showed an increase for the group 2 compared with the group 1, 3 and 4, respectively (P<0,05). Whithin the limits of the present study, it can be concluded that PTH in the absence or presence of CSI may be minimize significantly the bone resorption associated with periodontitis / Doutorado / Periodontia / Doutor em Clínica Odontológica

Orientadores: Pedro Luiz Rosalen, Francisco Carlos Groppo, Toshihisa Kawai / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-08T05:44:44Z (GMT). No. of bitstreams: 1 Franco_GilsonCesarNobre_D.pdf: 2005090 bytes, checksum: e5ea5ec57b82c8e2fa17e200ad139928 (MD5) Previous issue date: 2007 / Resumo: Doxiciclina (Dox) é um antimicrobiano pertencente à família das tetraciclinas com um amplo espectro de ação contra bactérias Gram-positivas e Gram-negativas. Além de suas propriedades antimicrobianas, Dox é atualmente empregada na periodontia como um modulador da resposta do hospedeiro (MRH), ao inibir a atividade da enzima metaloproteinase de matriz (MMP), a qual está relacionada ao processo de destruição tecidual. Neste contexto, este trabalho teve os seguintes objetivos: 1-determinar os parâmetros farmacocinéticos e integrar os índices PK/PD da Dox para o plasma, fluido gengival (FG) e saliva; 2-analisar os efeitos in vitro e in vivo da Dox sobre a osteoclastogênese com a finalidade de elucidar possíveis propriedades biológicas adicionais deste fármaco como MRH. Para a análise farmacocinética, 12 voluntários receberam dose oral única de 100 mg de Dox. Sangue, FG e saliva foram coletados em tempos pré-determinados e a concentração da Dox nestes fluidos foi determinada por bioensaio. A análise dos principais índices PK/PD da Dox foi realizada considerando o CIM para P. gingivalis. Para o segundo objetivo, o efeito da Dox sobre os processos de diferenciação e ativação osteoclástica foi verificado, respectivamente, pela contagem de células TRAP+ multinucleadas geradas a partir de células precursoras estimuladas com sRANKL na presença ou ausência de Dox e pela análise das lacunas de reabsorção formadas por estas células, quando cultivadas sobre discos de dentina. In vivo, o efeito da Dox sobre a osteoclastogênese foi determinado através da indução deste processo em calvária de camundongo. Solução de sRANKL/LPS foi injetada na região da calvária e os animais receberam, por gavagem, Dox ou placebo diariamente. Após 10 dias, a calvária foi removida para análise histoquímica. Em acréscimo, a atividade da Dox sobre a expressão de genes responsáveis pelos processos de diferenciação e ativação osteoclástica foi analisada por RT-PCR. Durante os experimentos in vitro e in vivo, a produção e atividade da MMP foram verificadas através de Western-blot e Zimograma respectivamente. Os resultados demonstraram que as maiores concentrações de Dox foram observadas no plasma, seguido pelo FG e saliva. A análise dos índices PK/PD da Dox indicou que a dose de 100 mg foi insuficiente para se obter os valores ideais antimicrobianos preconizados na /CIM. Os experimentos in vitro e in vivo sobre o efeito da Dox como MRH demonstraram que este fármaco inibiu os processos de diferenciação e ativação dos osteoclastos. Dox também modulou a expressão de proteínas diretamente relacionadas a osteoclastogênese, incluindo TRAP, Catepsina K e c-Myc. Finalmente, embora a síntese da MMP não tenha sido afetada, a atividade da MMP foi reduzida na presença de Dox. Portanto, os resultados do presente estudo sugerem que uma dose inicial maior do que 100 mg é necessária para alcançar o valor preconizado para ASC/CIM e Cmax/CIM, com a finalidade de se obter os melhores resultados clínicos antimicrobianos. A análise da Dox como MRH indicou que este fármaco pode atuar neste processo não somente pela sua capacidade de inativar a MMP, e sim, por apresentar a propriedade de inibir a diferenciação e ativação osteoclástica, incluindo a modulação de sua expressão gênica. literatura para os parâmetros ASC/CIM e Cmax / Abstract: Doxycycline (Dox), a member of the tetracycline family, is an antimicrobial agent with a broad-spectrum of activity against Gram-positive and Gram-negative bacteria. In addition to its antimicrobial properties, Dox is used in the treatment of periodontal diseases as a host response modulator by inhibiting the activity of an important enzyme, matrix metalloproteinase (MMP), which is related to the process of tissue destruction. In this context, this study had the following aims: 1-to determine the pharmacokinetic parameters of Dox and to integrate the PK/PD indices for plasma, gingival crevicular fluid (GCF) and saliva; 2-to analyze the effects in vitro and in vivo of Dox on the osteoclastogenesis and on the osteoclast activation in order to elucidate additional biological properties of Dox on the host response modulation (HRM). Twelve volunteers received single oral administration of Dox (100 mg). Blood, GCF and saliva were collected and the concentrations were measured by bioassay technique. The PK/PD analyses were carried out using the MIC for P. gingivalis. For the second objective, the effect of Dox on the osteoclast differentiation and activation processes was determined, respectively, by the counting of TRAP+ multinuclear cells derived from osteoclast precursory cells sRANKL-stimulated in the presence or absence of Dox and by the analysis of the resorption areas formed by these cells when cultured on dentin discs. In vivo, Dox¿s effect on the osteoclastogenesis was verified using the model of osteoclastogenesis induction in mouse calvaria. sRANKL/LPS was injected in the supra-calvaria area and the animals received Dox or placebo daily by gavage. After the experimental period of 10 days, the calvariae were removed for histochemistry analyses. In addition, the effect of Dox on the expression of genes related to the osteoclast differentiation and activation processes was carried out using RT-PCR technique. MMP production and activity were ensured during in vitro and in vivo experiments by Western-blot and Zymography, respectively. The results demonstrated that Dox achieved the highest concentration in the plasma, following by GCF and saliva. PK/PD analyses showed that the dose of 100 mg was insufficient to get the antimicrobial levels indicated in the literature for AUC/MIC and Cmax/MIC indices. In vitro and in vivo studies of Dox¿s effects on the HRM demonstrated that this drug could inhibit the osteoclast differentiation and activation process. Dox also showed an important property of down-regulation in the expression of proteins directly related to osteoclastogenesis, including TRAP, Cathepsin K and c-Myc. Finally, although Dox did not affect the expression of MMP protein, MMP activity was remarkably decreased by Dox. Therefore, the present study suggests that higher doses than 100 mg would be necessary to obtain effective antimicrobial levels and the effect of DOX on the HRM can be due to not only by MMP inhibition but also by the direct effect on RANKL-mediated osteoclast differentiation and activation, including its gene regulation / Doutorado / Farmacologia, Anestesiologia e Terapeutica / Doutor em Odontologia

Abstract Bone resorbing osteoclasts require tight attachment of their plasma membrane to the bone surface in order to retain the specific microenvironment and thus to be able to dissolve the bone matrix underneath. Cadherins are transmembrane glycoproteins usually mediating homophilic calcium-dependent cell-cell adhesion. In the present work we have studied the effects of the cadherin CAR sequence HAV-containing hexapeptide AHAVSE on osteoclasts. The primary attachment of osteoclasts to bone surface is not affected by the peptide, suggesting that it is not mediated by cadherins. Treatment of osteoclast cultures with AHAVSE decreased the number of resorption pits and the total resorbed area. Furthermore, we show rapid inactivation of osteoclasts with AHAVSE, which is seen as a decrease in the percentage of osteoclasts with actin rings. Pan-cadherin antibodies localized cadherin-like molecule in the sealing zone area of osteoclasts. These results suggest that cadherin-like molecules may mediate the tight attachment of osteoclasts in the sealing zone area and that the decrease of resorption in AHAVSE-treated osteoclast cultures is due to prevention of sealing zone formation. We studied the polarity of mesenchymal osteoblasts using osteosarcoma cell line UMR-108 and endosteal osteoblasts in situ in bone tissue cultures. Immunofluorescence confocal microscopy revealed that the vesicular stomatitis virus glycoprotein (VSV G) was targeted to the culture medium-facing surface. In endosteal osteoblasts, VSV G protein was found in the surface facing the bone marrow and circulation. On the contrary, Influenza virus hemagglutinin (HA) was localized to the bone substrate-facing surface of the UMR-108 cells. Electron microscopy showed that VSV particles were budding from the culture medium-facing surface, whereas Influenza viruses budded from the bone substrate-facing plasma membrane. These findings suggest the bone attaching plasma membrane of osteoblasts is apical, and the circulation or bone marrow facing plasma membrane is basolateral in nature. Gap junctions often mediate communication between different cells and cell types. In the present work, we demonstrate that rat osteoclasts show connexin-43 staining localizing in the plasma membrane of the cells in cell-cell contacts and over the basolateral membrane of osteoclasts. The effects of heptanol and Gap 27, known gap- junctional inhibitors, were studied using the well-characterized pit formation assay. The inhibitors decreased the number and activity of osteoclasts, suggesting a defect in the fusion of mononuclear osteoclast precursors to multinucleated mature osteoclasts. Furthermore, the total resorbed area and the number of resorption pits also decreased in the cultures. These results suggest that gap-junctional connexin-43 plays a functional role in osteoclasts, and that the blocking of gap junctions decreases both the number and the activity of osteoclasts.

Abstract The improvement of implant biocompatibility is constantly under investigation. Titanium is a standard biomaterial that performs well in dental and orthopedic implantations. However, detrimental adverse effects resulting from e.g. biomaterial properties, inflammatory responses and surgical procedures occasionally occur. Coating the biomaterials aims at increasing the proportion of successful operations. Pectins, large plant cell wall polysaccharides, are innovative, modifiable, and potentially anti-inflammatory candidates for biomaterial nanocoatings. In this thesis, covalently-grafted pectin fragments (modified hairy regions, MHRs) modified either in vitro (from apple) or in vivo (from potato) were tested. Cell culture vessels and titanium substratum coated with the apple-MHRs, MHR-A and a further-tailored fragment type, MHR-B, were compared with controls for their ability to support proliferation and differentiation of osteoclasts and osteoblasts. Cells grew and differentiated on MHR-B and on the control surfaces; MHR-A did not perform well in these assays. Genetically-engineered potato MHRs did not support bone cell growth to the same extent as apple MHR-B, but nonetheless the possibility to manipulate cellular proliferation with specific in vivo – modifications of pectins was introduced. When implanted into rat soft tissues, neither of the apple MHRs provoked severe acute inflammatory reactions, which indicates good in vivo - tolerance of these botanical macromolecules. These studies illustrate the biocompatibility of MHRs, and the directions towards which they could be further tailored. In terms of clinical use, their tolerability in vivo is especially significant.

La maladie de Paget est caractérisée par un remodelage osseux anarchique débutant par une phase de résorption excessive suivie d’une phase de formation désordonnée. Comme les ostéoclastes sont recrutés en plus grand nombre et sont hyperactifs aux sites affectés par la maladie, cette cellule a été incriminée dans ce désordre osseux. Le phénotype de l’ostéoclaste pagétique comporte de plus un défaut du processus autophagique, de même qu'une résistance à l'apoptose, dont les mécanismes restent mal connus. Certains facteurs génétiques et environnementaux contribuent en partie au phénotype, mais d'autres facteurs pourraient y être associés. Des travaux du laboratoire ont mis en évidence six événements de l’épissage alternatif associés à la maladie de Paget. Parmi les gènes identifiés, le gène TBC1D25 et ses deux isoformes connus n’ont jamais été étudiés dans l’ostéoclaste. Le gène TBC1D25 possède un domaine hautement conservé TBC régulant l’activité des petites GTPases Rabs dans le transport vésiculaire et un domaine LIR liant la protéine LC3 durant le processus de l’autophagie. Ces domaines fonctionnels se retrouvent seulement dans l’isoforme long. L’hypothèse de recherche est que l’altération de l’épissage alternatif du gène TBC1D25 dans les ostéoclastes pagétiques explique en partie le phénotype de la cellule. Le changement dans le ratio de l’expression des isoformes affecterait le processus de l’autophagie, en plus d’affecter la principale fonction de l’ostéoclaste, la résorption osseuse. L’objectif principal de l’étude est de caractériser l’expression et la fonction de TBC1D25 dans les ostéoclastes humains. Des ostéoclastes humains différenciés à partir de monocytes fœtaux ont été utilisés pour l’étude de la fonction de TBC1D25 dans l’autophagie, l’apoptose et la résorption osseuse. Les travaux ont permis de localiser les protéines dans l’ostéoclaste dans des conditions maintenant un niveau basal de l’autophagie et dans des conditions induisant l’autophagie. L’interaction entre TBC1D25 et Rab34 a été confirmée pour la première fois dans les ostéoclastes. De plus, une variation de cette interaction a été observée dans les différentes conditions modulant le niveau d’induction de l'autophagie. Les résultats préliminaires montrent une augmentation du ratio LC3II/LC3I lors de la diminution de l’expression de TBC1D25 dans des conditions augmentant l’induction de l'autophagie. Par contre, aucun effet a été observé sur la résorption osseuse ou sur l'apoptose lors de la diminution de l’expression de TBC1D25. En conclusion, les résultats préliminaires montrent que TBC1D25 préviendrait l’augmentation du ratio LC3II/LC3I dans l’ostéoclaste soit en inhibant l’induction de l’autophagie ou en favorisant la dégradation des autophagosomes par l’entremise de son action sur Rab34. / Abstract : Paget’s disease of bone (PDB) is characterized by increases in bone turnover starting with excessive resorption followed by disorganized bone formation. Because the initial phase of PDB involves excessive bone resorption, osteoclasts have been identified as the cells primarily affected in PDB. Pagetic osteoclasts are overactive, resistant to apoptosis and exhibit defects in autophagy, but the mechanisms involved are still unclear. While genetic and environmental factors associated with PDB may partially account for the osteoclast phenotype, other genetic contributors have been identified. Recent work from our laboratory has identified six alternative splicing events associated with PDB. Among those genes, TBC1D25 and its two known isoforms have never been studied in osteoclasts. The two functional domains of TBC1D25 (TBC and LIR) are only present in the long isoform. The highly conserved TBC domain regulates small Rab GTPases in vesicular transport and the LIR domain interacts with LC3 during autophagy. Our research hypothesis is that altered alternative splicing of TBC1D25 in pagetic osteoclasts could contribute to phenotype. Differential isoform expression could affect osteoclast autophagy and bone resorption. The aim of the study is to characterize the expression and function of TBC1D25 proteins in human osteoclasts. Osteoclasts differentiated from cord blood monocytes were used to investigate the function of TBC1D25 in autophagy, apoptosis and bone resorption. First, the localization of the protein has been characterized in conditions maintaining basal autophagy and in rapamycin-induced autophagy. Interactions between TBC1D25 and Rab34 have been observed for the first time in osteoclasts. Moreover, changes in the interaction were observed with autophagy induction. Preliminary results suggest increases in LC3II/LC3I ratio with decreasing TBC1D25 expression when autophagy induction is stimulated. On the other hand, preliminary results showed that decreased expression of TBC1D25 did not affect bone resorption, nor apoptosis. In conclusion, preliminary results show that in osteoclasts, TBC1D25 could prevent the increase of LC3II/LC3I ratio by inhibiting autophagy induction or by promoting the clearance of autophagosomes through its action on Rab34.