Dissertations / Theses on the topic 'Porphyromonas gingivalis'
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1
Loomer, Peter Michael. "The direct effects of Porphyromonas gingivalis 2561 on bone formation and mineral resorption in vitro." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27685.pdf.
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Meuric, Vincent. "Virulence de Porphyromonas gingivalis." Rennes 1, 2008. http://www.theses.fr/2008REN1B197.
Abstract:
"Porphyromonas gingivalis est une bactérie anaérobie stricte responsable des maladies parodontales. La respiration et la régulation des gènes de virulence restent inconnues. Ce travail explore la chaîne respiratoire et montre l'aérotolérance de la bactérie. Les résultats affirment la capacité de transmission aéroportée et inter individus par des mécanismes activant des gènes de résistance au stress oxydatif tel que "tpx" sous la dépendance d'OsyR régulateur transcriptionnel. Après une analyse de la littérature sur les principaux gènes de virulence, hémagglutinines et gingipaïnes, les études expérimentales ont montré que l'oxygène atmosphérique n'influence pas leur expression. Par contre, la coagrégation "in vitro" avec "T. Denticola", autre parodontopathogène, entraîne la surespression de "hagA", "rgpA" et "kgp" et par ce phénomène favorise le développement de la maladie parodontale. "
3
Hoppe, Tatjana [Verfasser]. "Maligne Transformation gingivaler Epithelzellen durch Porphyromonas gingivalis / Tatjana Hoppe." Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/1140525883/34.
4
Lobos, Matthei Ignacio Felipe. "Regulación de survivina en células epiteliales gingivales infectadas por Porphyromonas gingivalis." Tesis, Universidad de Chile, 2014. http://www.repositorio.uchile.cl/handle/2250/117229.
Abstract:
Memoria para optar el título de BioquímicoLa periodontitis crónica es una enfermedad de etiología infecciosa, caracterizada por la respuesta inflamatoria e inmune exacerbada por parte del hospedero que produce la destrucción de tejidos de soporte del diente. Actualmente, se postula que para el establecimiento de esta patología se produce una sucesión ecológica desde una comunidad microbiana asociada a salud hacia una asociada a enfermedad periodontal. En esta sucesión es imprescindible la presencia de ciertos patógenos que faciliten el remodelamiento de la microbiota oral y la progresión hacia enfermedad, siendo Porphyromonas gingivalis un patógeno clave en este proceso. P. gingivalis es una bacteria anaerobia estricta capaz de invadir y permanecer al interior de células epiteliales gingivales. Interesantemente, la infección por P. gingivalis produce una mayor viabilidad celular, mediante la modulación de proteínas relacionadas con apoptosis. Se ha sugerido que la proteína inhibidora de la apoptosis, survivina, podría contribuir a la inhibición de la apoptosis mediada por P. gingivalis; sin embargo, su participación en este proceso no está completamente dilucidada. En esta memoria de título se estudió si P. gingivalis es capaz de modular los niveles de survivina en la línea celular de epitelio gingival OKF6/TERT2 y si esta modulación está relacionada con el grado de virulencia de la bacteria. Para ello, se infectaron células OKF6/TERT2 utilizando dos cepas de referencia y un aislado clínico, cada una con diferente virulencia. Luego, se determinaron los niveles de proteína y transcrito de survivina a tiempos tempranos y tardíos post-invasión, mediante Western blot y RT-PCR. Los resultados obtenidos indican que P. gingivalis es capaz de disminuir los niveles de survivina y que esta modulación podría estar relacionada con la virulencia de la bacteria. Sin embargo, la disminución de survivina no estaría relacionada directamente con la inhibición de apoptosis que genera la infección por P. gingivalis
Chronic periodontitis is an infectious disease characterized by an exacerbated inflammatory and immune response by the host, which causes the destruction of the tooth supporting tissues. Nowadays, it is assumed that for the onset of this pathology an ecological succession from a bacterial community associated to health, to one associated with periodontal disease is produced. In this succession, the presence of certain pathogens facilitate the remodeling of the oral microbiota and the consequent progression to disease, being Porphyromonas gingivalis a key pathogen in this process. P. gingivalis is a strict anaerobic bacterium capable of invading and persisting within gingival epithelial cells. Interestingly, infection by P. gingivalis produce an increase in the viability of these cells by modulation of apoptosis related proteins. It has been suggested that the apoptosis inhibitory protein, survivin, could contribute to the inhibition of apoptosis mediated by P. gingivalis; however, its participation in this process is still unknown. In this work, we studied whether P. gingivalis is capable of modulate survivin levels in gingival epithelial cells OKF6/TERT2 and if this modulation is related to bacterial virulence. To achieve this goals we infected OKF6/TERT2 cells with two reference strains and one clinical isolate, each with different virulence. Survivin protein and transcript levels were determined at early and late post-infection times by Western blot and RT-PCR. The results of this work indicated that P. gingivalis is capable of decreasing survivin levels and this modulation could be related to virulence features of the bacterium. Nevertheless, survivin decrease would not be directly related to the inhibition of apoptosis induced by P. gingivalis
5
Bugueño, Valdebenito Isaac Maximiliano. "Caracterización de aislados clínicos de Porphyromonas gingivalis y su efecto en la viabilidad de células epiteliales gingivales." Tesis, Universidad de Chile, 2014. http://www.repositorio.uchile.cl/handle/2250/130110.
Abstract:
Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaLa periodontitis es una enfermedad infecciosa multifactorial, caracterizada por una respuesta inflamatoria exacerbada que produce la destrucción de las estructuras que dan soporte al diente, incluyendo la encía, el ligamento periodontal, el cemento radicular y el hueso alveolar. Para la iniciación de las periodontitis, se requiere la presencia de una comunidad bacteriana subgingival compleja en la cual coexisten diversos géneros y especies microbianas. Dentro de las especies del complejo rojo de Socransky que contribuyen a la etiología de la enfermedad periodontal, está Porphyromonas gingivalis (P. gingivalis). P. gingivalis es una bacteria Gram negativo que tendría especial relevancia en la progresión de la periodontitis. Entre los factores de virulencia de P. gingivalis se encuentran el lipopolisacárido (LPS), las fimbrias y el antígeno K o cápsula, los cuales están involucrados en el proceso de infección. La expresión de estos factores de virulencia por parte de la bacteria, puede variar de manera importante entre individuos, generando una respuesta distinta en los tejidos infectados, como en células epiteliales gingivales. Se ha descrito que P. gingivalis puede invadir las células epiteliales de la encía y modular diferentes vías de señalización que generen inhibición de la activación del sistema inmune e inhibición de la apoptosis celular. En este trabajo, se evaluaron características de la envoltura celular, y propiedades macro y microscópicas de aislados clínicos de P. gingivalis y cepas de referencia, y se evaluó su efecto sobre la viabilidad de células epiteliales gingivales. De esta manera, se analizaron parámetros macromorfológicos de las cepas en medios sólido y líquido. Se evaluó la capacidad de formación de biopelículas, la carga superficial (mediante ensayos de unión a citocromo C y ensayos de hidrofobicidad), se estudió la presencia de cápsula (tinción con tinta china) y caracterizó los perfiles electroforéticos del LPS. Finalmente, se estudió la viabilidad y el nivel de apoptosis de células epiteliales gingivales infectadas por 9 dos cepas virulentas de referencia y 7 aislados clínicos de P. gingivalis, utilizando la línea celular OKF6/TERT2. Estos ensayos fueron realizados en tiempos tempranos, intermedios y tardíos de infección. Nuestros resultados mostraron diferencias en el crecimiento entre aislados clínicos de individuos sanos comparados con enfermos, tanto en medio sólido como en medio líquido. En la mayoría de los aislados clínicos se observó presencia de cápsula. Además, todos formaron más biopelículas que las cepas de referencia, y no se encontraron diferencias significativas entre las muestras de pacientes sanos y enfermos. Adicionalmente, la mayoría de los aislados clínicos presentó una mayor carga superficial que las cepas de referencias. Nuestros resultados también mostraron que todos los aislados clínicos y cepas de referencia de P. gingivalis fueron capaces de invadir células OKF6/TERT2. Adicionalmente, observamos que algunos aislados clínicos aumentaron significativamente la viabilidad celular a tiempos tempranos y tardíos de infección, incluso más que la cepa W50 descrita como una cepa muy virulenta y altamente invasiva. En síntesis, nuestros resultados indican que existen diferencias macromorfológicas y de envoltura celular entre aislados clínicos de P. gingivalis provenientes de individuos sanos y enfermos y que la infección por P. gingivalis mantiene o aumenta la viabilidad en la línea celular derivada de epitelio gingival OKF6/TERT2, como consecuencia de la modulación de la apoptosis. También, observamos que éste fenómeno es dependiente de la virulencia de la cepa. La virulencia se relaciona con características de la envoltura celular y con la presencia de ciertos componentes específicos. Estos aislados clínicos más virulentos podrían estar asociados a cuadros clínicos más agresivos.
6
Maley, Janette. "Genetic studies on Porphyromonas gingivalis W83." Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/35395.
Abstract:
Until recently molecular biological approaches to the study of putative virulence factors of the oral pathogen Porphyromonas gingivalis were limited. This was due to the absence of a genetic system which could facilitate the production of isogenic mutant derivatives. Among the many components produced, the capsule is believed to be of particular importance in the pathogenicity of P. gingivalis. In order to identify mutants lacking capsular polysaccharide, purified capsular material from P. gingivalis W83 was used to generate capsule-specific antisera. However, these antisera contained antibodies which recognised lipopolysaccharide. The use of polymyxin B-agarose was found to be useful in the removal of LPS-reactive material. Capsular polysaccharide was purified further and shown to be free of detectable LPS. A system for conjugal transfer of plasmid DNA from Escherichia coli to P. gingivalis was developed. This method was then used for the introduction of the suicide-vector R751::Tn4351?4 into P. gingivalis. Examination of a number of P. gingivalis Tn4351 mutants demonstrated the presence of multiple copies of Tn4351 in the chromosome of the mutants. Recovery of plasmid pNJR12 from P. gingivalis transconjugants led to the isolation of IS 1126. This insertion sequence was present in the chromosome of all strains of P. gingivalis examined but absent from other members of the genus. The amino acid sequence of the major open reading frame (ORF1) was derived from the nucleotide sequence of IS 1126. ORF1 contained the conserved motifs displayed by the transposase proteins of IS-elements belonging to the IS4 family.
7
Xie, Hua. "Regulation of fimbrillin expression in Porphyromonas gingivalis." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6392.
8
Rodrigues, Richelle Soares. "PrevalÃncia de Porphyromonas gingivalis, genÃtipo fima II de Porphyromonas gingivalis e Aggregatibacter actinomycetemcomitans em indivÃduos com periodontite agressiva generalizada." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11486.
Abstract:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorConselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Porphyromonas gingivalis e Aggregatibacter actinomycetemcomitans sÃo periodontopatÃgenos associados à periodontite agressiva. A fÃmbria, uma estrutura relacionada à adesÃo e à invasÃo de cÃlulas, à um dos principais fatores de virulÃncia de P. gingivalis. Baseado na sequÃncia de nucleotÃdeos, seis genÃtipos(fimA) que codificam a fÃmbria principal dessas bactÃrias foram identificados, sendo o fimA II mais comumente relacionado à destruiÃÃo periodontal. O objetivo deste trabalho foi avaliar, por meio de reaÃÃo em cadeia da polimerase em amostras de placa subgengival dos sÃtios com maior profundidade de sondagem de pacientes com periodontite agressiva, a prevalÃncia de P. gingivalis, do genÃtipo fimA II de P. gingivalis e de A. actinomycetemcomitans, assim como relacionar a presenÃa desses patÃgenos ou genÃtipo à idade e aos parÃmetros clÃnicos periodontais (Ãndice de placa, Ãndice de sangramento gengival, profundidade de sondagem e nÃvel de inserÃÃo) encontrados nesses pacientes. Foram selecionados 45 pacientes com periodontite agressiva generalizada, com idade entre 15 e 40 anos. Nessa populaÃÃo, 64,4% apresentaram P. gingivalis e 28,8% apresentaram A. actinomycetemcomitans em sua microbiota subgengival. Dos pacientes positivos para P. gingivalis, 82,6% apresentaram o genÃtipo fimA II. Ao se relacionar a presenÃa ou ausÃncia das bactÃrias ou genÃtipo aos dados clÃnicos e idade, foi observada diferenÃa estatisticamente significante entre o nÃvel clÃnico de inserÃÃo do sÃtio coletado de pacientes com presenÃa de P. gingivalis e seu genÃtipo fimA II quando comparados aos pacientes negativos para essa bactÃria e genÃtipo, sendo a perda de inserÃÃo significativamente maior em pacientes que apresentaram P. gingivalis e em paciente com seu genÃtipo fimA II. AlÃm disso, foi encontrada mÃdia de idade significativamente mais elevada em pacientes positivos para P. gingivalis que em pacientes negativos para essa bactÃria. Concluiu-se, assim, que P. gingivalis e seu genÃtipo fimA tipo II estÃo presentes em alta prevalÃncia em pacientes com periodontite agressiva, que A. actinomycetemcomitans està presente em menor proporÃÃo de indivÃduos na populaÃÃo estudada e que P. gingivalis parece ser mais comumente encontrada em bolsas mais profundas e em indivÃduos mais velhos.
Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans are periodontal pathogens associated with aggressive periodontitis. The fimbriae, a structure related to adhesion and invasion of cells, is one of the major virulence factors of P. gingivalis. Based on the nucleotide sequence, six genotypes(fimA) encoding the major fimbriae of these bacteria were identified, and the fimA II is the most commonly associated with periodontal destruction. The objective of this study was to evaluate, by polymerase chain reaction in subgingival plaque samples from sites with highest probing depth in patients with aggressive periodontitis, the prevalence of P. gingivalis, P. gingivalis genotype fimA II and A. actinomycetemcomitans, and relate the presence of these pathogens or genotype to age and clinical periodontal parameters (plaque index, gingival bleeding index, probing depth and clinical attachment level) in these patients. We selected 45 patients with generalized aggressive periodontitis, aged from 15 to 40 years. 64.4% of these patients harbored P. gingivalis and 28.8% harbored A. actinomycetemcomitans in their subgingival microbiota. In patients positive for P. gingivalis, 82.6 % presented the genotype fimA II. In relation to the presence or absence of bacteria or gene to clinical data and age, a statistically significant difference between clinical attachment level was observed in the selected sites of patients with the presence of P. gingivalis and its genotype fimA II when compared to patients negative for these bacteria and genotype, with periodontal loss significantly higher in patients harboring P. gingivalis and in patients harboring genotype fimA II. In addition, the average age in patients positives for P. gingivalis was significantly higher than in negative ones. It is therefore concluded that P. gingivalis and its genotype fimA II are present in high prevalence in patients with aggressive periodontitis, A. actinomycetemcomitans is present in a smaller proportion of individuals in the studied population and P. gingivalis seems to be more commonly found in deeper sites and older individuals.
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Rodrigues, Richelle Soares. "Prevalência de Porphyromonas gingivalis, genótipo fima II de Porphyromonas gingivalis e Aggregatibacter actinomycetemcomitans em indivíduos com periodontite agressiva generalizada." reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/7904.
Abstract:
RODRIGUES, Richelle Soares. Prevalência de Porphyromonas gingivalis, genótipo fima II de Porphyromonas gingivalis e Aggregatibacter actinomycetemcomitans em indivíduos com periodontite agressiva generalizada. 2014. 44 f. Dissertação (Mestrado em Odontologia) - Universidade Federal do Ceará. Faculdade de Farmácia, Odontologia e Enfermagem, Fortaleza, 2014.Submitted by denise santos (denise.santos@ufc.br) on 2014-04-04T13:13:32Z No. of bitstreams: 1 2014_dis_rsrodrigues.pdf: 909297 bytes, checksum: 47ad16e66062d057016963a13334a1f2 (MD5)
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Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans are periodontal pathogens associated with aggressive periodontitis. The fimbriae, a structure related to adhesion and invasion of cells, is one of the major virulence factors of P. gingivalis. Based on the nucleotide sequence, six genotypes(fimA) encoding the major fimbriae of these bacteria were identified, and the fimA II is the most commonly associated with periodontal destruction. The objective of this study was to evaluate, by polymerase chain reaction in subgingival plaque samples from sites with highest probing depth in patients with aggressive periodontitis, the prevalence of P. gingivalis, P. gingivalis genotype fimA II and A. actinomycetemcomitans, and relate the presence of these pathogens or genotype to age and clinical periodontal parameters (plaque index, gingival bleeding index, probing depth and clinical attachment level) in these patients. We selected 45 patients with generalized aggressive periodontitis, aged from 15 to 40 years. 64.4% of these patients harbored P. gingivalis and 28.8% harbored A. actinomycetemcomitans in their subgingival microbiota. In patients positive for P. gingivalis, 82.6 % presented the genotype fimA II. In relation to the presence or absence of bacteria or gene to clinical data and age, a statistically significant difference between clinical attachment level was observed in the selected sites of patients with the presence of P. gingivalis and its genotype fimA II when compared to patients negative for these bacteria and genotype, with periodontal loss significantly higher in patients harboring P. gingivalis and in patients harboring genotype fimA II. In addition, the average age in patients positives for P. gingivalis was significantly higher than in negative ones. It is therefore concluded that P. gingivalis and its genotype fimA II are present in high prevalence in patients with aggressive periodontitis, A. actinomycetemcomitans is present in a smaller proportion of individuals in the studied population and P. gingivalis seems to be more commonly found in deeper sites and older individuals.
Porphyromonas gingivalis e Aggregatibacter actinomycetemcomitans são periodontopatógenos associados à periodontite agressiva. A fímbria, uma estrutura relacionada à adesão e à invasão de células, é um dos principais fatores de virulência de P. gingivalis. Baseado na sequência de nucleotídeos, seis genótipos(fimA) que codificam a fímbria principal dessas bactérias foram identificados, sendo o fimA II mais comumente relacionado à destruição periodontal. O objetivo deste trabalho foi avaliar, por meio de reação em cadeia da polimerase em amostras de placa subgengival dos sítios com maior profundidade de sondagem de pacientes com periodontite agressiva, a prevalência de P. gingivalis, do genótipo fimA II de P. gingivalis e de A. actinomycetemcomitans, assim como relacionar a presença desses patógenos ou genótipo à idade e aos parâmetros clínicos periodontais (índice de placa, índice de sangramento gengival, profundidade de sondagem e nível de inserção) encontrados nesses pacientes. Foram selecionados 45 pacientes com periodontite agressiva generalizada, com idade entre 15 e 40 anos. Nessa população, 64,4% apresentaram P. gingivalis e 28,8% apresentaram A. actinomycetemcomitans em sua microbiota subgengival. Dos pacientes positivos para P. gingivalis, 82,6% apresentaram o genótipo fimA II. Ao se relacionar a presença ou ausência das bactérias ou genótipo aos dados clínicos e idade, foi observada diferença estatisticamente significante entre o nível clínico de inserção do sítio coletado de pacientes com presença de P. gingivalis e seu genótipo fimA II quando comparados aos pacientes negativos para essa bactéria e genótipo, sendo a perda de inserção significativamente maior em pacientes que apresentaram P. gingivalis e em paciente com seu genótipo fimA II. Além disso, foi encontrada média de idade significativamente mais elevada em pacientes positivos para P. gingivalis que em pacientes negativos para essa bactéria. Concluiu-se, assim, que P. gingivalis e seu genótipo fimA tipo II estão presentes em alta prevalência em pacientes com periodontite agressiva, que A. actinomycetemcomitans está presente em menor proporção de indivíduos na população estudada e que P. gingivalis parece ser mais comumente encontrada em bolsas mais profundas e em indivíduos mais velhos.
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Herrera, Bustamante Sergio Humberto. "Variabilidad del LPS de Porphyromonas gingivalis y Porphyromonas endodontalis en dientes con periodontitis apical asintomática." Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/137646.
Abstract:
Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaLa Periodontitis Apical Asintomática (PAA) corresponde a una patología periapical de origen infeccioso que se caracteriza por la respuesta negativa a los tests de sensibilidad pulpar del diente afectado y por presentar, al examen radiográfico, un área radiolúcida peri y/o pararadicular. Histológicamente se puede clasificar como quiste radicular inflamatorio (QRI) o granuloma periapical (GP). Las comunidades microbianas asociadas a la PAA se caracterizan por infectar el sistema de canales radiculares (SCR) de los dientes y son muy variables en su composición, existiendo diferencias entre diferentes poblaciones geográficas, así como también dentro de una misma población. Porphyromonas gingivalis y Porphyromonas endodontalis, son especies bacterianas que se han visto asociadas a este tipo de infección, por medio de la interacción de sus factores de virulencia con las células del hospedero. Dentro de estos factores de virulencia está el lipopolisacárido (LPS), constituyente de la membrana externa de la pared celular más abundante de la superficie de ambas especies bacterianas y que podría explicar los efectos deletéreos en la destrucción del ligamento periodontal y del hueso, influyendo así en el aumento del tamaño de las lesiones apicales de origen endodóntico (ALEO). En este trabajo, realizamos una caracterización del perfil estructural del LPS de Porphyromonas gingivalis y Porphyromonas endodontalis y analizamos la variabilidad de éste entre los aislados obtenidos. Con este objetivo, inicialmente analizamos macromorfológicamente los cultivos en medio líquido y sólido de aislados clínicos de P. gingivalis y P. endodontalis, obtenidos de exudado periapical proveniente de dientes con diagnóstico de Periodontitis Apical Asintomática y luego caracterizamos el perfil electroforético del LPS en geles de SDS-poliacrilamida teñido con Nitrato de Plata de ambas especies bacterianas y las comparamos con sus respectivas cepas de referencia. Nuestros resultados mostraron una baja cantidad de canales radiculares infectados con P. gingivalis y P. endodontalis. Las características macromorfológicas de dichos microorganismos resultaron bastante similares a las de las cepas de referencia, sin embargo, se observaron diferencias entre ambas. En cuanto al perfil electroforético del LPS de ambas especies, pese a tener pocos aislados clínicos positivos para ambas, si hubo diferencias en el perfil electroforético de sus LPS, siendo más marcadas en las colonias de P. endodontalis. En síntesis, nuestros resultados indican que P. gingivalis y P. endodontalis están presentes en canales radiculares de dientes diagnosticados con PAA y que existen diferencias en las especies bacterianas estudiadas, tanto en sus características macromorfológicas, como en las características de sus LPS.
OD59MMIC2015
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11
Houalet-Jeanne, Sylvie. "Etude in-vitro de l'internalisation de Porphyromonas gingivalis dans la cellule pariétale gingivale." Rennes 1, 2001. http://www.theses.fr/2001REN1B085.
Abstract:
Porphyromonas gingivalis (P. Gingivalis) est décrit comme l'un des pathogènes majeurs de la maladie parodontale. Il est également impliqué dans l'étiologie de pathologies systémiques. A ce jour, les mécanismes précis de son pouvoir de virulence gardent d'importantes zones d'ombre. Le travail présenté ici, s'applique à confirmer le potentiel invasif de la bactérie face à la cellule hôte, et à préciser son devenir dans la cellule épithéliale. L'utilisation de différents marqueurs sur un modèle in vitro, nous a permis de détecter P. Gingivalis au sein de cellules épithéliales de lignée KB en Microscopie Confocale, et d'analyser divers aspects de l'adhérence et de l'internalisation. Parallèlement, nous employons les techniques de culture sur gélose au sang, en enceinte anaérobie.
12
Al-Qutub, Montaser Nazmi. "Lipopolysaccharide lipid A structural heterogeneity of Porphyromonas gingivalis /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6383.
13
Yuan, Lihui. "Quorum sensing regulated gene expression in Porphyromonas gingivalis." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010043.
Abstract:
Thesis (Ph.D.)--University of Florida, 2005.Typescript. Title from title page of source document. Document formatted into pages; contains 134 pages. Includes Vita. Includes bibliographical references.
14
Ally, Nafisa. "The specificity of proteinase-adhesins from Porphyromonas gingivalis." Monash University, Dept. of Biochemistry and Molecular Biology, 2003. http://arrow.monash.edu.au/hdl/1959.1/9477.
15
Fawell, Stuart Colin. "Polymorphism in the rag locus of porphyromonas gingivalis." Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412704.
16
Muzahim, Kzar Ryam. "Porphyromonas gingivalis inducerar frisättningav IL-8 från monocyter." Thesis, Örebro universitet, Institutionen för hälsovetenskap och medicin, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-37667.
17
Bhatti, Manpreet. "A study of the photolysis of Porphyromonas gingivalis." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311934.
18
Abusleme, Ramos Loreto Andrea. "Genotipificación de porphyromonas gingivalis en pacientes con periodontitis." Tesis, Universidad de Chile, 2009. http://repositorio.uchile.cl/handle/2250/135077.
Abstract:
Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaAutor no autoriza el acceso a texto completo de su documento
La periodontitis es un tipo de enfermedad periodontal que afecta a los tejidos de inserción de las piezas dentarias. En la actualidad, entre los agentes etiológicos que tienen mayor participación en la génesis de las periodontitis, destacan A. actinomycetemcomitans y las bacterias pertenecientes al complejo rojo. P. gingivalis presenta diversos factores de virulencia, como su capacidad de adherencia a los tejidos periodontales y a otras bacterias, el LPS de su pared celular y múltiples proteasas. Las bases moleculares de sus mecanismos de virulencia y su relación con la diversidad genética no han sido suficientemente comprendidos aún. El propósito del presente estudio es genotipificar aislados de P. gingivalis obtenidos de pacientes con Periodontitis Crónica y Agresiva utilizando una metodología basada en la “Secuencia de Inserción” (IS1126). Se tomaron muestras de biofilm subgingival en 4 sitios por paciente (uno por cuadrante). Para ello se utilizaron conos de papel estériles y se depositaron en RTF frío hasta su procesamiento en el laboratorio. Se obtuvo, mediante cultivo, bacterias pigmentadas de negro para su posterior identificación fenotípica, molecular y genotipificación, de los aislados confirmados mediante PCR como P. gingivalis. De un total de 58 aislados se identificaron por PCR 47 de ellos y se logró genotipificar 35, caracterizándose 7 perfiles genéticos diferentes. Un 66,6% de los pacientes presentaron un solo genotipo en sus aislados, mientras que el 33,3% mostró dos perfiles genéticos distintos. El grupo de pacientes estudiados presentó variabilidad genética a nivel de la secuencia IS1126, encontrándose 7 genotipos diferentes en todos los aislados analizados.
19
Schlenker, Courtney. "The Characterization of PG0228 in Porphyromonas gingivalis W83." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/219.
Abstract:
Periodontitis affects 10 to 15 percent of most adult populations and can contribute to numerous systemic diseases. Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized prime causative agent in periodontitis. Studies have shown a number of small non-coding RNAs (sRNAs) have been related to bacterial virulence. Many of these sRNAs require the facilitation of the bacterial Sm-like protein, Hfq, for optimum function. Hfq is a RNA chaperone involved in RNA stability, sRNA function, and polyadenylation. Mutants lacking in Hfq often show pleiotropic phenotypes, although the extent and severity of hfq null phenotypes is often species-specific. Hfq has been encoded by nearly half of eubacteria, including pathogens. Based on a standard BLAST search, hfq has not been detected in P. gingivalis. It is highly likely, however, that the bacterium possesses an Hfq homologue due to its importance as an overall RNA cofactor. The P. gingivalis hypothetical protein, PG0228, possesses the Sm-like protein motif, thus we believe it is an excellent Hfq candidate. Our goal was to characterize PG0228 so we can gain a better insight into the function of this hypothetical protein and determine if it indeed behaves like Hfq. Microarray analysis, growth studies, and a survival study were done on a Δ0228 mutant to determine the biological role of the protein encoded by PG0228. PG0228 was also tagged in vivo in order to determine if the protein binds to RNA. Our results show P. gingivalis deficient in PG0228 show significant similarities to other bacterium deficient in hfq. The Δ0228 strain showed significant sensitivity to host defense mechanisms and an overall gene regulation in 15% of the genome. In addition, the mutant is viable but produces a lower final cell density. Thus, we believe PG0228 is an excellent Hfq candidate, and suggest further studies will show PG0228 is an Hfq homologue.
20
Dwyer, Holly. "Characterization of putative Porphyromonas gingivalis RNA-binding proteins." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3550.
Abstract:
Porphyromonas gingivalis (P. gingivalis) is a gram-negative, anaerobic bacterium recognized as a major player in progression of periodontal disease. P. gingivalis survives in the oral cavity while being exposed to dynamic environmental conditions such as pH, temperature, nutrient availability and host immune responses such as oxygen tension and nitrosative stress. Survival and pathogenesis of P. gingivalis in the oral cavity require mechanisms to regulate gene expression in response to the extracellular signals. Little is known about the regulatory mechanisms of P. gingivalis in the oral cavity, so it is important to investigate and characterize these regulatory mechanisms. Adaptation to environmental cues using riboregulation is a significant mechanism for post-transcriptional regulation in bacteria. Using bioinformatics, we have identified a putative RNA-binding protein in P. gingivalis: RBP. Bioinformatic studies have led to the selection of HUβ and HUα nucleoid associated proteins as controls for RNA binding. I hypothesize that the candidate proteins RBP, HUβ and HUα bind RNA in P. gingivalis. The first aim is to show that RBP, HUβ and HUα bind RNA. Using electrophoretic mobility shift assays with IRE RNA and synthesized RNA motifs, I have confirmed that the proteins do bind RNA. The second aim is to isolate and sequence the P. gingivalis RNA that bind to RBP, HUβ and HUα. I have isolated the RNAs that bound the proteins and determined identity of the RNA using high throughput sequencing. Finally, I have identified an antibody that specifically binds RBP to use for in vivo immunoprecipitation of RNA-protein complexes from P. gingivalis. In conclusion RBP, HUβ and HUα are novel RNA binding proteins in P. gingivalis, and further investigation of these proteins is necessary to understand the mechanisms of gene regulation in P. gingivalis.
21
Singh, Umadatt. "The adherence properties of Bacteroides gingivalis." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31013.
Abstract:
A Bacteroides gingivalis adhesin mediating attachment to red blood cells and buccal epithelial cells was isolated, cloned and characterized. The isolation procedure involved gentle stirring of the cells followed by ammonium sulphate precipitation, ion-exchange and gel chromatography. The native molecule had a Mr in excess of 10⁶ kDa and was made up of subunits with an Mr of 43 kDa. Antisera raised to the adhesin and its subunits reacted with antigens on the surface of B. gingivalis cells. No reaction with fimbriae was seen. The IgG fractions from these antisera inhibited the adherence of B. gingivalis to host tissue. Proteolytic enzymes destroyed binding capability of whole cells and of the purified adhesin but the molecular weight of the haemagglutinin was not altered.
A genomic library of B. gingivalis DNA was created in E. coli JM83. 5500 colonies were screened by a colony immunoassay with anti-S. gingivalis serum and by a direct haemagglutinating assay. 337 clones tested positive by the immunoassay and two clones, 1-3,and 1-49 tested positive for haemagglutinating activity. Both haemagglutinating positive recombinants had inserts of 3.2 kb. One clone, 1-49 was chosen for further characterization. E. coli 1-49 expressed a protein of 43 kDa that was not present in E. coli JM 83 control as seen by SDS-PAGE and Western blot analysis. Anti-1-49 serum inhibited the haemagglutinating activity of B. gingivalis and E. coli 1-49. This serum reacted with surface molecules on B. gingivalis and E. coli 1-49 as seen by immunogold electron microscopy and immunofluorescence, and to the purified haemagglutinin by Western blot analysis. Like the haemagglutinin on B. gingivalis, the haemagglutinating activity of E. coli 1-49 was destroyed by heating and proteolytic enzymes but the apparent size of the molecule as determined by SDS-PAGE was not affected.
A bacterial coaggregating adhesin from B. gingivalis was isolated and characterized.
The isolation procedure involved adsorption of the solubilized adhesin on S. mitis followed by elution with glycine buffer. SDS-PAGE of the boiled adhesin revealed a protein with an Mr of 46 kDa. Proteolytic digestion destroyed all bacterial aggregating activity and hydrolysed the 46 kd protein. Antisera raised to the 46 kDa protein reacted with surface molecules on all strains of B. gingivalis tested. This antiserum inhibited the coaggregation reaction between B. gingivalis and other bacteria.
Vesicles produced by B. gingivalis were found to enhance the binding of S. sanguis to serum coated hydroxy apatite (SeHA). Maximum vesicle mediated binding took place at 37°C and was destroyed by heating.
The lipopolysaccharide from several black pigmented bacteroides were isolated and characterized physically, chemically and immunologically. All of the LPS were of the smooth type and contained the sugars rhamnose, glucose, galactose, glucosamine and galactosamine; no KDO or heptose were found.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
22
Shelburne, C. E. "Stress-induced P. gingivalis gene expression in periodontal disease." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269172.
23
Díaz, Patricia I. "Studies on the oxidative stress response of porphyromonas gingivalis : a thesis submitted in fulfillment of the requirements for admission to the degree of Doctor of Philosophy /." Title page, summary and table of contents only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phd5426.pdf.
24
Fariña, Espinosa Valeska Gissel. "Respuesta inmune humoral y endotexemia en infección endodóntica con Porphyromonas endodontalis y Porphyromonas gingivalis en periodontitis apical asintomática." Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/137589.
Abstract:
Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaIntroducción: La periodontitis apical asintomática (PAA) corresponde a una patología de etiología polimicrobiana que resulta en la destrucción del periodonto apical debido a una reacción inflamatoria crónica. Existe evidencia creciente de que infecciones crónicas en la cavidad oral pueden producir diseminación de productos bacterianos e inflamatorios a la circulación general y activación del sistema inmune con posible inducción de efectos sistémicos adversos. El potencial efecto sistémico asociado a PAA y en especial, a la infección endodóntica por Porphyromonas endodontalis y Porphyromonas gingivalis aún no ha sido investigado. El objetivo de este estudio fue determinar la respuesta inmune humoral y endotoxemia en pacientes con PAA en infección endodóntica con Porphyromonas endodontalis y Porphyromonas gingivalis versus pacientes controles sanos. Material y métodos: Se incluyeron 17 pacientes con diagnóstico de PAA de entre 18 a 34 años de edad, sin enfermedades o factores de riesgo de ECV y 24 controles sanos. Se tomaron muestras de suero a todos los pacientes del estudio y muestras de canales radiculares a los individuos con PAA. Se realizó identificación de aislados de P. endodontalis y P. gingivalis mediante cultivos bacterianos específicos, PCR y secuenciación. Se midió concentración de endotoxinas en suero mediante ensayo comercial Limulus Amebocyte Lysate y niveles de anticuerpos IgG e IgA contra las bacterias anteriormente mencionadas por ensayo ELISA multiserotipo. Los datos fueron analizados mediante el software stata v12. Se determinó significancia estadística con un p<0.05. Resultados: En pacientes con PAA se detectó P. gingivalis en el 11.76% y P. endodontalis en el 29.4% de las muestras. Se observó un aumento de niveles de LPS en suero de pacientes con PAA respecto a controles, pero esta diferencia no fue estadísticamente significativa. Se encontraron diferencias significativas en niveles de endotoxinas (p=0.002) y anticuerpos IgG (p=0.0047) en pacientes con PAA en los que se detectó P. endodontalis versus los que no presentaban la bacteria. Conclusiones: Las especies bacterianas P. endodontalis y P. gingivalis fueron identificadas en canales radiculares de individuos afectados por PAA. En pacientes con PAA existe una tendencia a presentar niveles séricos mayores de endotoxinas y anticuerpos IgG e IgA anti P. endodontalis y P. gingivalis versus individuos sanos, pero sin diferencias estadísticamente significativas. Existen niveles significativamente mayores de anticuerpos IgG anti P. endodontalis en pacientes con PAA con infección endodóntica por este patógeno versus pacientes con PAA en los que no se identificó la bacteria.
25
Palm, Eleonor. "Inflammatory responses of gingival fibroblasts in the interaction with the periodontal pathogen Porphyromonas gingivalis." Doctoral thesis, Örebro universitet, Institutionen för hälsovetenskap och medicin, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-38660.
26
Bainbridge, Brian W. "Generation and function of Porphyromonas gingivalis lipid A heterogeneity /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/6394.
27
Zark, S. "Mechanisms of immunomodulation by the periodontal pathogen Porphyromonas gingivalis." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546428.
28
Belfield, Louise Alicia. "Interactions between porphyromonas gingivalis and macrophages in oral pathology." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1611.
Abstract:
Macrophages play a fundamental role in driving both inflammatory and immunosuppressive conditions of the oral mucosa. Periodontitis, a chronic inflammatory condition affecting the supporting structures of the teeth, is widely prevalent, affecting a large proportion of the global population, and has been linked to the development of systemic inflammatory diseases. Oral squamous cell carcinoma (OSCC) is placed sixth in the WHO rankings of cancer incidence worldwide, and despite continuing research into underlying mechanisms, incidence is on the rise. Aberrant macrophage function has been implicated in the pathogenesis of both diseases. On recruitment to sites of inflammation, macrophages become polarised within a spectrum of effector phenotypes depending on the factors they encounter in their microenvironment. These cells are highly plastic and continuously adapt their effector functions in response to locally derived stimuli. Mechanisms have been developed by pathogenic bacteria and transformed host tissues to exploit this plasticity and manipulate macrophage phenotype to facilitate disease progression. However, this plasticity is also available for therapeutic manipulation. The main objectives of this study therefore were to investigate the interactions between macrophages and pathogenic stimuli in the context of oral pathology with a view to identifying novel therapeutic targets. Firstly, a reproducible model of M1 and M2 macrophage polarisation using the THP-1 cell line was established to study their interactions with pathogenic stimuli. Treating the cells with combinations of PMA plus IFNγ or IL-4 for 24 hours led to two distinct populations of cells: PMA + IFNγ treated cells expressed higher levels of pro-inflammatory cytokines TNFα, IL-1β and IL-6, but lower levels of IL-10 and TGF-β, characteristic of M1 macrophages. PMA + IL-4 treated cells expressed lower levels of TNFα, IL-1β and IL-6 and higher levels of IL-10 and TGF-β, characteristic of M2 macrophages. As P. gingivalis LPS is present in the developing periodontal lesion, cytokine expression from macrophages exposed to LPS during polarisation was investigated. Exposure of macrophages to 1 μg/ml Pg LPS during polarisation led to a statistically significant down-regulation of inflammatory cytokines TNFα (10-, 4- and 5.5 –fold decrease in PMA, M1 and M2 cells, respectively) and IL-1β (1.9-, 2.0- and 1.5 –fold decrease in PMA, M1 and M2 macrophages, respectively) in response to subsequent stimulation with LPS. IL-6 production was not affected. The same pattern of cytokine down regulation was observed regardless of LPS species used, and in most cases, at a lower dose of 1 ng/ml LPS during polarisation. Finally, as macrophages recruited to the tumour environment will be influenced by tumour-secreted factors, the response of macrophages to LPS stimulation in the presence of OSCC conditioned media was examined. Contrariwise to polarisation with LPS, exposure of macrophages to OSCC produced factors during polarisation led to an amplification of IL-1β (13.8-, 2.3- and 8.8 –fold increase in PMA, M1 and M2 cells, respectively), and IL-6 (16.8-, 17.3- and 44.9 –fold increase in PMA, M1 and M2 cells, respectively), but not TNFα in response to LPS. Counter intuitively, these findings suggest that LPS manipulation of macrophage polarisation might result in a more M2 –like population of cells, whereas OSCC produced factors may result in a more M1- like population of cells. Viewed therapeutically, one short, single exposure of macrophages to LPS would up-regulate pro-inflammatory cytokines, whereas prolonged or chronic exposure would lead to the down-regulation of pro-inflammatory cytokines, therefore, LPS as a therapeutic modulator of macrophage function in an immunosuppressive (M2) environment to an inflammatory environment (M1) would only be viable as a single dose. For chronic inflammatory disease however, a repasted or prolonged exposure of macrophages to LPS skews macrophages to display a more M2-like cytokine profile and could dampen down detrimental pro-inflammatory cytokine production. The continued study of macrophage/ P. gingivalis interactions may shed light on pathogenic mechanisms not only in oral pathological conditions, but in a range of diseases.
29
Montenegro, Chipana Alex. "Actividad antibacteriana de Caesalpinia spinosa (tara) sobre Porphyromonas gingivalis." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2014. https://hdl.handle.net/20.500.12672/3723.
Abstract:
La periodontitis es una enfermedad de etiología infecciosa que presenta como síntomas el sangrado e inflamación de encías, movilidad dentaria, recesiones gingivales, en las que diversas enfermedades sistémicas favorecen su progresión. Uno de estos agentes más importantes es Porphyromonas gingivalis, especie bacteriana anaeróbica estricta, Gram negativo. A su vez, el uso de antibióticos sistémicos está indicado sólo en ciertos tipos de periodontitis, y no siempre el tratamiento es exitoso. Hoy en día, tanto en medicina general como odontológica, se está investigando nuevas alternativas de tratamientos antibacterianos, dado el continuo aumento de la resistencia bacteriana a los antibióticos convencionales y por las reacciones adversas que estos producen en algunos pacientes.
El objetivo principal de este trabajo de investigación es determinar la actividad antibacteriana de un extracto alcohólico de Caesalpinia spinosa “tara” sobre cepas de Porphyromonas gingivalis. Este estudio es de tipo experimental, prospectivo, comparativo e in vitro. Se llevó a cabo en el Laboratorio de Microbiología de la Facultad de Odontología de la UNMSM.
Para realizar este estudio se utilizó cepas de Porphyromonas gingivalis previamente identificadas por los laboratorios MICROBIOLOGIC, las cuales fueron importadas a través de una Casa Comercial “GENLAB”.
El estudio investigó la actividad antibacteriana, del extracto alcohólico de Caesalpinia spinosa “tara” en cinco concentraciones (6,25 mg/ml; 12,5 mg/ml; 25 mg/ml; 50 mg/ml y 75 mg/ml) sobre la cepa ATCC 33277 Porphyromonas gingivalis mediante el test de difusión en Agar, se encontró que el extracto alcohólico de la Caesalpinia spinosa (tara) posee actividad antibacteriana sobre Porphyromonas gingivalis, aunque entre las cinco concentraciones no existe diferencia significativa.Tesis
30
Sai, Suhasini Yanamandra. "Role of Extracytoplasmic Function Sigma Factors in Porphyromonas gingivalis." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/488.
Abstract:
Porphyromonas gingivalis is a major etiological agent that is responsible for the cause and progression of periodontal diseases. The bacterium is exposed to various environmental conditions and oxidative stress conditions while it is in the oral cavity. So, P. gingivalis should have an efficient regulatory system in order to adjust and survive in the oral cavity. But little is known about the regulatory mechanisms that help the bacteria to survive in the oral cavity. So, it is essential to understand and characterize these regulatory mechanisms. The response and adaptation of P. gingivalis to environmental stress conditions occur at the level of transcription which involves the alternative sigma factors. Extracytoplasmic function (ECF) sigma factors are the largest group of alternative sigma factors that play a major role in bacterial response to environmental stress conditions. Here we characterize the σ-70 factor, SigH and SigG, the extracytoplasmic function sigma factors encoded in P. gingivalis genome. Our results show that the expression of SigH is upregulated when P. gingivalis is grown in the presence of oxygen. However, there is no change in the expression of SigG when grown in the presence of oxygen. Furthermore several genes involved in oxidative stress protection such as sod, trx, tpx, ftn, feOB and the hemin uptake locus, hmu, are downregulated in the mutant deficient in SigH designated as V2948. Our RNA-seq analysis of SigG showed that there is no change in the regulation of genes involved in oxidative stress protection and metal homeostasis in SigG deficient mutant designated as V3085. Our survival studies showed that both SigH and SigG are essential for P. gingivalis to grow in host cells. Collectively our studies demonstrate that SigH is a positive regulator of gene expression required for survival of the bacterium in the presence of oxygen and oxidative stress, hemin uptake and virulence. However our studies show that SigG is essential for the bacteria to grow in host cells and hence helps in the virulence of P. gingivalis.
31
Warren, Cheyanne. "The Response of HN4 Cells to Porphyromonas gingivalis DNA." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1572.
Abstract:
Periodontal disease is one of the most common human diseases. Bacteria trigger the onset and progression of the disease and among them Porphyromonas gingivalis has been demonstrated to be a major etiologic agent. Although the interaction of the bacterium with the host is of major importance for the understanding of the disease mechanisms, both the host as well as the pathogen components involved in the interaction remain poorly understood. One of the bacterial components capable of eliciting a host response is unmethylated CpG DNA motifs found in bacteria. Thus, the first aim was to determine the response of oral epithelial cell line, HN4, to challenge with genomic DNA derived from P. gingivalis. Microarray analysis revealed that at a level of 2-fold or more, 95 genes were regulated after 6 hrs, and 33 genes were regulated after 24 hrs post infection with P. gingivalis DNA when compared to unchallenged HN4 cells. Furthermore, since the Toll-like receptor 9 (TLR9) was demonstrated to be critical in generating the innate immune response to both bacterial and viral unmethylated CpG DNA in immune cells as well as some epithelial cell lines, investigation of the expression and localization of this receptor in HN4 cells was examined. In addition, changes in TLR9 expression and localization in response to HN4 cells challenged with P. gingivalis DNA was also investigated. Our flow cytometry results indicated that the receptor is present intracellularly but interestingly, is also detected on the cell surface. Last, shRNA technology was employed to down-regulate TLR9 expression in HN4 cells. This would provide a useful tool for future studies examining the role of TLR9 in mediating the host response to genomic DNA derived from P. gingivalis and other periodontopathogens.
32
Paranjape, Anuya R. "Investigating the transcriptional regulation by OxyR in Porphyromonas gingivalis." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/413.
Abstract:
Periodontal diseases are bacterially induced, inflammatory diseases which are responsible for loss of alveolar bone and connective tissue supporting the teeth which results in loss of teeth. Gram negative anaerobic bacteria are highly associated with these diseases. One of them is Porphyromonas gingivalis belonging to the phylum Bacteroidetes. Infection by P. gingivalis is recurrent after physical removal of the bacteria from the oral cavity and even after antibiotic treatment as development of resistance is not rare. Hence complete understanding the biology of this bacterium is of significance. This gram negative obligate anaerobe, being aerotolerant, manages to survive inside the oral cavity, where oxidative stress is ubiquitous. Genome sequence of P. gingivalis shows the presence of a transcriptional regulator OxyR which is a homologue of OxyR present in E. coli. P. gingivalis OxyR induces the expression of antioxidant defense genes like sod, ahpC-F, dps to protect the bacteria from oxidative stress. Expression of P. gingivalis OxyR regulon is not very well understood. Microarray studies carried out in our lab using P. gingivalis W83 to study gene regulation by OxyR, indicated that several genes in P. gingivalis are co-regulated by iron-and OxyR. Literature also supports that in iron deplete conditions genes involved in oxidative stress are down-regulated. These studies formed the basis of our hypothesis that OxyR might regulate the genes in P. gingivalis in an iron dependent manner. To study the mechanism of regulation by P. gingivalis OxyR and to determine whether OxyR regulation is iron dependent, two approaches were applied - in vitro characterization of binding and in vivo characterization. First step of in vitro characterization was to perform CHIP-chip assay to determine OxyR-binding sites present on the genomic DNA of P. gingivalis. As this assay was performed under completely anaerobic conditions, the target fragments to which OxyR was found to bind during this assay were not same as reported in literature. These and the fragments reported in literature were used for EMSA. EMSAs carried out using crude cell lysates and in vitro OxyR protein preparations showed expected results but the results were not reproducible. In vivo expressed and purified P. gingivalis OxyR never bound to the target fragments used. Preparation of a stable protein preparation and improvement in the parameters of EMSA is very important to further investigate the binding in vitro. The second approach is based on in vivo characterization of binding. This requires tagging the P. gingivalis OxyR at its C-terminus with fluorescent protein to observe its binding to the target DNA sequences. Fluorescently tagged OxyR, is expected to emit fluorescence from a highly localized area to produce sharp fluorescent spots when it is bound to its target sequences. Unbound OxyR is expected to emit a fluorescent signal which is spread over the entire area of the cell. This technique will help to determine the conditions under which OxyR binds to its target DNA sequences. This provides a means to confirm the results obtained from in vitro characterization instead of just extrapolating them.
33
Belvin, Benjamin. "HcpR of Porphyromonas gingivalis utilizes heme to bind NO." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/639.
Abstract:
The obligate anaerobe Porphyromonas gingivalis is the etiological agent responsible for periodontal disease. It must withstand high levels of reactive nitrogen species in the oral cavity generated by the host and other oral flora. The mechanisms allowing for protection against such stress remain poorly understand. HcpR is an FNR-CRP family regulator that has been implicated in regulation of the nitrosative stress response. In this study we characterize the biochemical properties of HcpR. It is a homo-dimer that is composed of 3 domains – a heme-binding domain, dimerization helix, and a DNA-binding domain. Our studies show that HcpR binds the heme cofactor. UV-Vis and Raman spectroscopy reveal that the bound heme is capable of binding the diatomic gas molecule Nitric Oxide (NO)-a source of nitrosative stress. Binding of NO causes a change in the oxidation state of the iron. SAXS reveals the protein bears a structural resemblance to homology models generated from an ortholog. Promoterr studies reveal that mechanisms P. gingivalis-HcpR uses to modulate expression are novel and different than those found in E. coli and P. aeruginosa.
34
Rostami, Soheil. "Characterization of a putative TonB deficient Porphyromonas gingivalis mutant." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3492.
Abstract:
Porphorymonas gingivalis is one of the major bacterial pathogens responsible for the initiation and progression of periodontal disease. The bacterium requires hemin uptake for its growth and has developed sophisticated mechanisms to extract hemin from hemin containing proteins in the oral cavity. Hemin first binds to receptors on the surface of P. gingivalis and is then taken up in an energy dependent manner. TonB is an inner membrane bound protein that spans the periplasm and is believed to be involved in the passage of hemin through the double membrane of P. gingivalis. However, the TonB protein in P. gingivalis is yet to be identified. We identified PG0785 as a possible P. gingivalis TonB based on its bioinformatics data showing similarity to other known TonB proteins. We generated a P. gingivalis mutant lacking a functional PG0785 and then characterized the mutant to determine the role of PG0785. We performed metal content and protease assays, virulence studies and transcriptional and translational analysis of our mutant and wild type P. gingivalis strains. Phenotypic studies showed that the mutant cannot accumulate hemin on its surface. The mutant has significantly lower levels of iron compared to wild type based on metal content assays. The mutant also has significantly lower protease activity compared to the wild type. Virulence studies showed that the mutant interacted and invaded eukaryotic cells at much lower levels than the wild type. These results allowed us to speculate that PG0785 is very important in binding of hemin to surface of P. gingivalis. PG0785 also plays an important role in iron uptake, protease activity and virulence of P. gingivalis. Transcriptional and translational analyses have shown that numerous TonB related genes, metal uptake genes, hemin uptake genes and genes related to virulence have been differentially regulated in the mutant lacking a functional PG0785 gene compared to the wild type strain. In conclusion we believe that based on our results PG0785 is a putative P. gingivalis TonB protein that plays a significant role in the biology of P. gingivalis.
35
Wu, Fan [Verfasser]. "Porphyromonas gingivalis induces PD-L1 upregulation in prostate cancer cells : impact of the periodontopathogenic bacterium Porphyromonas gingivalis on prostate cancer cells / Fan Wu." Gießen : Universitätsbibliothek, 2021. http://d-nb.info/1233036661/34.
36
Meléndez, Stefony Martina Cassandra. "Tipificación de Aggregatibacter actinomycetemcomitans y Porphyromonas gingivalis en pacientes afectados con periodontitis." Tesis, Universidad de Chile, 2013. http://www.repositorio.uchile.cl/handle/2250/117483.
Abstract:
Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaIntroducción: Las periodontitis son un conjunto de enfermedades infecciosas, caracterizadas por la destrucción de los tejidos de inserción de los dientes, cuya causa es el biofilm subgingival. Porphyromonas gingivalisy Aggregatibacter actinomycetemcomitansson bacterias periodonto-patógenas del biofilm subgingival que han sido ampliamente asociadas al inicio, progresión y severidad de la enfermedad.Sobre la base de la cápsula extracelular de P. gingivalis y del Opolisacárido del LPS de A. actinomycetemcomitans se han descrito distintos serotipos bacterianos, denominados K1-K6 y a-f, respectivamente. En distintas poblaciones afectadas de periodontitis, se ha establecido que los serotipos bacterianos más frecuentemente detectados son los serotipos K5 y K6de P. gingivalisy b-cde A. actinomycetemcomitans. En Chile no existen estudios que hayan analizado la frecuencia de detección de estos serotipos bacterianos. Objetivos: Cuantificar la frecuencia de detección de los distintos serotipos de P. gingivalis y A.actinomycetemcomitans en pacientes afectados de periodontitis crónica o periodontitis agresiva. Metodología:Muestras microbiológicas del biofilm subgingival fueron obtenidas de 25 sitios periodontales distintos en pacientes con periodontitis crónica o agresiva. La presencia de P. gingivaliso A. actinomycetemcomitans se estableció identificando las características de las colonias microbianas en cultivo en agar sangre hemina/menadiona o agar TSVB,pruebas bioquímicas de metanol o catalasay por identificación mediante PCR de la subunidad 16Sdel RNA ribosomal (rRNA). Purificados bacterianos fueron aislados y la caracterización del serotipo de P. gingivalis y de A. actinomycetemcomitans se realizó mediante PCR utilizando partidores específicos. Resultados:P. gingivalisfue identificado en el 40% de los pacientes afectados de periodontitis, tanto crónica como agresiva, y A. actinomycetemcomitans en un 16%. Cuando P. gingivalis fue detectado, el 60% fue serotipo K3 y el 50% K2 o K5. En el caso deA. actinomycetemcomitans, el 75% fue serotipo b y el 25% c. 6 Conclusión:En los pacientes con periodontitis existe una frecuencia variable de detección de los distintos serotipos bacterianos. En P. gingivalis los serotipos más frecuentemente detectados fueron el serotipo K3, K2y K5 y en A. actinomycetemcomitans el serotipo b.
37
Blasi, Beriain Ignacio. "Porphyromonas gingivalis LPS stimulates autophagy using a TLR mediated pathway." Doctoral thesis, Universitat Internacional de Catalunya, 2017. http://hdl.handle.net/10803/461098.
Abstract:
Resum:
Porphyromonas gingivalis often subverts host cell autophagic processes for its own survival. Our previous studies document the association of the cargo sorting protein, melanoregulin (MREG), with its binding partner, the autophagic protein, microtubule-associated protein 1 light chain 3 (LC3) in macrophages incubated with P. gingivalis (strain 33277). Differences in the lipid A moiety of lipopolysaccharide (LPS) affect the virulence of P. gingivalis; penta-acylated LPS1690 is a weak Toll-like receptor 4 agonist compared with Escherichia coli LPS, whereas tetra-acylated LPS1435/1449 acts as an LPS1690 antagonist. To determine how P. gingivalis LPS1690 affects autop- hagy we assessed LC3-dependent and MREG- dependent processes in green fluorescent protein (GFP)-LC3-expressing Saos-2 cells. LPS1690 stimu- lated the formation of very large LC3-positive vac- uoles and MREG puncta. This LPS1690-mediated LC3 lipidation decreased in the presence of LPS1435/1449. When Saos-2 cells were incubated with P. gingivalis the bacteria internalized but did not traffic to GFP-LC3-positive structures. Never- theless, increases in LC3 lipidation and MREG puncta were observed. Collectively, these results suggest that P. gingivalis internalization is not necessary for LC3 lipidation. Primary human gin- gival epithelial cells isolated from patients with periodontitis showed both LC3II and MREG puncta whereas cells from disease-free individu- als exhibited little co-localization of these two pro- teins. These results suggest that the prevalence of a particular LPS moiety may modulate the degradative capacity of host cells, so influencing bacterial survival.
38
Geraldo, Barbara Maria Corrêa. "Efeito antimicrobiano e imunomodulador de Lactobacillus reuteri em cultura de osteoblastos e Galleria mellonella desafiados por Porphyromonas gingivalis /." São José dos Campos, 2017. http://hdl.handle.net/11449/151089.
Abstract:
Orientador: Ana Lia AnbinderBanca: Maria Aparecida Neves Jardini
Banca: Débora Pallos
Resumo: Os tratamentos mais usados para periodontite são a raspagem e aplainamento radicular, tratamento não cirúrgico, associado ou não ao uso de antimicrobianos. No entanto, novas terapias têm sido testadas com foco na modulação da resposta do hospedeiro. Alguns micro-organismos têm efeitos benéficos na saúde dos seres humanos, pois produzem efeitos antimicrobianos e anti-inflamatórios, os chamados probióticos. O presente trabalho avaliou o efeito antimicrobiano de Lactobacillus reuteri sobre Porphyromonas gingivalis e a influência deste probiótico em sua forma viva, morta (paraprobiótico) e sobrenadante em modelo de invertebrado Galleria mellonella, infectado por P. gingivalis. Posteriormente, foi determinada a viabilidade celular, níveis de óxido nítrico e de interleucina (IL)-1βb, IL-6, IL-17 e fator de necrose tumoral (TNF)- α, através do ensaio de ELISA em osteoblastos infectados por LPS de P. gingivalis in vitro. Os dados foram submetidos ao teste estatístico ANOVA, Kruskal-Wallis ou Log-rank (Mantel-Cox), com nível de significância de 5%.L. reuteri e seu sobrenadante possuem a mesma atividade antimicrobiana. O probiótico viável e o morto apresentaram efeitos iguais na sobrevivência de G. mellonella e L. reuteri vivo foi o único que aumentou densidade hemocitária das lagartas. O probiótico e o paraprobiótico reduziram igualmente os níveis IL-1β, IL-6, TNF-α e IL-17, sendo que o paraprobiótico, diferentemente do lactobacilo vivo, reduziu significantemente as quantidades de IL-... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The most used treatments for periodontitis are scaling and non-surgical root planing, associated or not to the use of antimicrobials. However, new therapies have been tested with a focus on host response modulation. Some microorganisms have beneficial effects on human health because they produce antimicrobial and antiinflammatory effects, called probiotics. The present study evaluated the antimicrobial effect of Lactobacillus reuteri on Porphyromonas gingivalis and the influence of this probiotic in its live, inactivated (paraprobiotic) form and supernatant on Galleria mellonella invertebrate model, after infection by P. gingivalis. Later, the cell viability, nitric oxide levels and interleukin (IL)-1b, IL-6, IL-17 and tumor necrosis factor (TNF)- α, by the Elisa assay, were evaluated in osteoblasts infected with P. gingivalis LPS in vitro. Data were submitted to ANOVA, Kruskal-Wallis or Log-rank (Mantel-Cox) statistical test, with a significance level of 5%. L. reuteri and its supernatant have the same antimicrobial activity. The viable and inactivated probiotic had equal effects in G. mellonella survival and L. reuteri alive was the only one that increased the hemocyte density in the invertebrate model. Probiotics and paraprobiotics also reduced levels of IL-1β, IL-6, TNF-α and IL-17 cytokines, whereas paraprobiotic, unlike living lactobacillus, significantly reduced the amounts of IL-6 and TNF-α, compare to the LPS control group. The highest reductions of the studied cytok... (Complete abstract click electronic access below)
Mestre
39
Suwannakul, Suttipalin. "Isolation of porphyromonas gingivalis that differs in epithelial cells invasion." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527233.
40
Rigg, Gordon P. "Molecular characterisation of PgaA, an antigen from periodontopathogen Porphyromonas gingivalis." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/35411.
Abstract:
Molecular cloning techniques were used to investigate antigenic determinants of periodontopathogen P. gingivalis in an attempt to begin to explore the cell surface of this organism. A genomic library generated in Escherichia coli was probed with polyclonal antiserum specific for P. gingivalis whole cells. Clone pGPR1, which contained a 307 bp fragment of P. gingivalis DNA sequence, was found to react with both polyclonal antiserum and a monoclonal antibody (mAb) specific for the trypsin-like protease of this organism (Brick190). This fragment was used to probe a second P. gingivalis genomic library. Clone pGPR2 was shown to hybidise with the 307 bp probe. DNA sequence analysis revealed pGPR2 contains a 5,653 bp insert with seven open reading frames one of which shows significant DNA homology with the rnhB gene of E.coli. The 307 bp probe sequence was found to reside within an ORF predicted to encode a 455 amino acid (50 kDa) protein and this ORF was designated pgaA (P. gingivalis antigen). The predicted amino acid sequence of PgaA contains a putative ABC signature for binding NTPs as well as a predicted transmembrane domain. Subclones of pgaA in expression vector pTTQ18* were found to be reactive with a mAb specific for a 46 kDa species-specific antigen of the cell envelope of P. gingivalis (LDS28) as well as Brick190. One such subclone, pGPR7 was also shown to express a 46 kDa protein reactive in western blots with mAb LDS28. Minicell labelling of pGPR2-encoded proteins using pGPR2 subclones revealed that pgaA directs expression of protein of multiple molecular weights (31-46 kDa) from its own promoter in E. coli, and that some of these forms may be caused by proteolysis of a 50 kDa precursor which itself shows a reduced apparent molecular weight (46 kDa) on SDS PAGE.
41
Montgomery, Anna Barbara Kay. "Porphyromonas gingivalis peptidylarginine deiminase in the aetiology of rheumatoid arthritis." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:b98d61c0-9863-4b20-a352-3737010fe8f1.
Abstract:
Anti-citrullinated protein antibodies (ACPA) are the main autoantibodies in rheumatoid arthritis (RA). Citrullination is the conversion of arginine to citrulline by peptidylarginine deiminase (PAD) enzymes. Periodontitis (PD) is a risk factor for RA, and there is evidence this may be due to citrullination by the unique prokaryotic PAD enzyme expressed by PD pathogen Porphyromonas gingivalis (PPAD). The aim of this work was to characterise PPAD, and investigate its potential role in the aetiology of RA. The 3D crystal structure of PPAD was solved, and functional residues identified. The catalytic domain comprises five ββαβ motif repeats, which create a canonical binding groove into the active site, and the immunoglobulin-like domain is an anti-parallel β-sandwich. PPAD lacks significant homology to human PADs, and forms distinct citrullinated peptides from those formed by human PAD isoforms PAD2 and PAD4 due to unique C-terminal substrate specificity. In vivo, immunisation with P. gingivalis proteins: PPAD, arginine gingipain (Rgp), and enolase (PgEnolase), induced ACPA responses in mice. In human cohorts, antibodies to PPAD, Rgp, and PgEnolase were increased in RA patients compared to osteoarthritis or healthy controls, and in RA patients with PD compared to those without. Six months of PD treatment saw a significant reduction in antibodies to P. gingivalis in RA patients with PD, but no change in ACPA. These results demonstrate P. gingivalis induces ACPA responses comparable to those observed in RA, potentially through formation of novel citrullinated peptides by PPAD. Structural and mechanistic information obtained here can be used in future studies targeting PPAD as a potential therapeutic strategy in RA.
42
Igboin, Christina. "Comparative genomic analysis and host-pathogen interactions of porphyromonas gingivalis." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1197405913.
43
He, Jia. "Identification and Characterization of Metal Uptake Loci in Porphyromonas gingivalis." Available to VCU users at :, 2007. http://hdl.handle.net/10156/1263.
44
Mirpanah, Jacob. "Biochemical Analysis of Putative RNA-Binding Proteins in Porphyromonas gingivalis." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5379.
Abstract:
BIOCHEMICAL ANALYSIS OF PUTATIVE RNA-BINDING PROTEINS IN PORPHYROMONAS GINGIVALIS
By Jacob Mirpanah
Bachelor of Arts in Biology, University of Virginia, 2015
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Physiology and Biophysics at Virginia Commonwealth University
Virginia Commonwealth University, 2018
Major Director: Janina P. Lewis, Ph.D., Philips Institute for Oral Health Research
RNA-Binding Proteins (RBPs) play important regulatory roles in countless cellular processes. Often via the induction of a structural change in RNA’s secondary structure, RBPs are known to modulate protein expression through post-transcriptional regulation. In Escherichia coli, such RBPs have been thoroughly studied and shown to display differential expression throughout the bacterial life cycle; suggesting their importance in prompting different events in the bacterial cell. Further, RNA- and DNA-recognition domains have been characterized in proteins Hub as well as RBP in E.coli and their nucleic acid ligands sequenced. It was our aim to extend this level of information to Hub and RBP as they exist in a main etiological agent in periodontal disease; Porphyromonas gingivalis. Using quantitative PCR expression analysis, we saw a general upregulation of both proteins in the logarithmic phase as compared to the stationary phase. This upregulation was most pronounced in PG0627, the putative analog of E. coli RBP in P. gingivalis. Further, Electrophoretic Mobility Shift Assays suggest sequence specific interaction of PG0627 to RNA. Uninhibited and Inhibited mobility assays seem to confirm that PG0627 binds with great specificity to a conserved RNA sequence. Quantitative measure of interaction came in the form of fluorescence anisotropy, which produced a Dissociation Constant (Kd) of approximately 53 nM; suggesting a high degree of affinity. Lastly, a mutant was generated in order to produce high quality RNA libraries to be sequenced through the Illumina MiSeq system. Sequencing data is still incoming.
45
Rojas, Celis Ana Victoria. "El Antígeno O de Porphyromonas gingivalis participa en la modulación de los niveles de Interleuquina-8 y de la migración en células epiteliales gingivales." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/170366.
Abstract:
Memoria para optar al título de BioquímicoLa periodontitis es una enfermedad inflamatoria crónica de las estructuras que soportan las piezas dentales, la cual está asociada a un proceso infeccioso causado por un cambio en la ecología local de la biopelícula bacteriana oral. Un 90% de la población chilena presenta signos clínicos de esta patología. Porphyromonas gingivalis (P. gingivalis) se ha propuesto como un agente etiológico clave en la periodontitis. En nuestro laboratorio, se obtuvieron aislados clínicos de P. gingivalis provenientes de individuos sanos, en los que se vio ausencia de la región del antígeno O (AgO) del lipopolisacárido (LPS). En cambio, en aislados clínicos provenientes de pacientes con periodontitis, el LPS está completo. Además, se ha observado anteriormente que cuando células de epitelio gingival (GECs, por sus siglas en inglés) eran infectadas con una cepa silvestre de P. gingivalis (W50) había un aumento del ARNm del Toll-like receptor 4 (TLR4), a diferencia de lo que ocurre cuando son infectadas con una mutante isogénica carente de AgO polimérico (cepa ΔPG1051), sugiriendo que el AgO sería importante para el reconocimiento de la bacteria. Una de las consecuencias de la activación de TLRs es el incremento en los niveles de citoquinas pro-inflamatorias. Esto se ha relacionado con un aumento en la capacidad migratoria en varios tipos celulares, incluyendo a GECs, donde la migración favorece la formación de saco periodontal
Periodontitis is a highly prevalent chronic inflammatory disease in Chile and worldwide that mainly affects the tissues supporting de teeth. This disease is associated with an infectious process caused by a change in the local ecology of the subgingival biofilm. It has been proposed that the bacterium Porphyromonas gingivalis (P. gingivalis) plays a key role in disease onset and progression because this bacterium induces dysbiosis that contributes to the inflammatory process. In a previous study from our group, we observed that the O antigen (OAg) region of the lipopolysaccharide contributes to the inhibition of apoptosis induced by P. gingivalis in epithelial cells, which correlates with an increase in the expression of TLR4. One of the consequences of the activation of TLRs is the increase in the levels of pro-inflammatory cytokines. This has been related to an increase in the migratory capacity of several cell types, including human oral epithelial cells, where enhanced migration is associated with formation of periodontal pockets. Considering this background, the objective was to determine if TLR4 activation mediated by AgO can increase the levels of pro-inflammatory cytokines and to promote migration an oral epithelial cell line OKF6 / TERT2. For this, the level of TLR4 (flow cytometry), TNF-α, IL-8 and IL-1β (multiplex) and migration (Boyden's chamber) were measured after infecting with the previously mentioned strains. Our results show that infection with P. gingivalis does not change the TLR4 levels on the surface of OKF6 / TERT2 cells, independent of the presence or absence of AgO. On the other hand, levels of IL-8 decreased only with the virulent strain of P. gingivalis W50, unlike the isogenic mutant in LPS that does not produce AgO, which does not change them. These changes are independent of TLR4. Finally, the strain with a complete LPS (W50) produces an increase in migration. However, in the absence of AgO there are not significant changes with respect to uninfected cells. In conclusion, in this work we found that the AgO of P. gingivalis participates in the modulation of pro-inflammatory marker levels (IL-8) and cell migration, which could contribute to the development of periodontitis
CONICYT-FONDAP 15130011; Fondecyt 1170925; FIOUCH 17/020
46
Herath, Mudiyanselage Thanuja Darshani Kumari Herath. "A systems biological study on heterogeneous Porphyromonas gingivalis lipopolysaccharides: human gingivalfibroblasts interaction : molecular mechanisms and implications inperiodontal pathogenesis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50162615.
Abstract:
Porphyromonas gingivalis is a keystone periodontopathogen and its lipopolysacharide (LPS) is strongly associated with periodontal disease. A long-standing controversy occurs on the role of P. gingivalis LPS in induction of innate host response in different cell types. It has recently been found that P. gingivalis LPS displays remarkable heterogeneity with both tetra- (LPS1435/1449) and penta-acylated (LPS1690) lipid A structures. However, the potential effects of heterogeneous structures of P. gingivalis LPS on modulating host innate responses in human gingival fibrobalsts (HGFs) - the most abundant cells in gingiva remain unclear. To fulfill this research gap, a comprehensive study on the P. gingivalis LPS-HGFs interations was undertaken.
The effects of P. gingivalis LPS1435/1449 and LPS1690 on the expression profiles of pro-inflammatory cytokines were investigated (Chapter III). P. gingivalis LPS1690 (not LPS1435/1449) significantly upregulated the expression of IL-6, IL-8 and TNF-α, suggesting that P. gingivalis LPS may differentially modulate the expression of pro-inflammatory cytokines. The effects of P. gingivalis LPS on the expression of MMPs 1-3 and TIMP-1, and regulation of MMP-3 were then determined (Chapter IV). P. gingivalis LPS1690 markedly induced MMP-3 expression through p38 MAPK and ERK signal pathways, whereas TIMP-1 was greatly upregulated by P. gingivalis LPS1435/1449. These findings suggest that P. gingivalis LPS heterogeneity may differentially modulate the expression and regulation of MMP-3. Based on these findings, the involvements of TLR2/4 and the downstream signaling pathways were explored (Chapter V). P. gingivalis LPS1690 induced TLR4 expression, whereas TLR2 was upregulated by P. gingivalis LPS1435/1449. NF-κB pathway played a dominant role in P. gingivalis LPS1690-induced expression of IL-6 and IL-8. These findings suggest that the two isoforms of P. gingivalis LPS critically interact with TLR2 and TLR4, and may determine the subsequent activation of signal transduction cascades that differentially modulate immuno-inflammatory response. P. gingivalis could thereby evade innate host defense and contribute to periodontal pathogenesis. To obtain a holistic profile of heterogeneous P. gingivalis LPS-HGFs interactions, a systems biology-based study through proteomics, metabolomics and bioinformatics approaches was undertaken (Chapter VI). Pro-inflammatory proteins (e.g. Cyclophilin, Annexins, IL-6 and Cathepsins) were induced by P. gingivalis LPS1690. In contrast, anti-inflammatory proteins (e.g. ANXA1, ANXA2 and Gal-1) were upregulated by P. gingivalis LPS1435/1449. P. gingivalis LPS1690 also induced antioxidant defense molecules like MnSOD and PRDXs. Secretomic analysis showed that immuno-inflammatory mediators, extra-cellular proteases and matrix proteins were differentially modulated by the two isoforms of P. gingivalis LPS as well. These findings demonstrate that host responses such as immuno-inflammatory activity, oxidative stress and anti-oxidant defense may be differentially modulated and regulated by the heterogeneous P. gingivalis LPS. Further study shows that P. gingivalis LPS1435/1449 and LPS1690 differentially modulate oxidative stress response and antioxidant expression, and differential regulation of MnSOD could be a critical determinant of periodontal homeostasis (Chapter VII).
The present findings may bring new insight into the molecular mechanisms of periodontal pathogenesis. Targeting the mechanisms of shift in lipid A structures of P. gingivalis LPS may be a potential strategy to develop novel approaches to control and prevent periodontal diseases.published_or_final_version
Dentistry
Doctoral
Doctor of Philosophy
47
Celis, Sersen Andrés Osvaldo. "Presencia de porphyromonas gingivalis, Genotipos fimA-I, II, III y IV, en un grupo de escolares chilenos de 4 a 8 años de edad." Tesis, Universidad de Chile, 2012. http://www.repositorio.uchile.cl/handle/2250/112097.
Abstract:
Trabajo de Investigación
Requisito para optar al Título de
Cirujano DentistaAutor no autoriza el acceso a texto completo de su tesis en el Portal de Tesis Electrónicas
INTRODUCCIÓN: Especies bacterianas anaeróbicas potencialmente patogénicas constituyen un porcentaje significativo de la microbiota normal de la cavidad bucal y hoy se sabe que su capacidad de colonizar y sobrevivir durante la niñez temprana, depende de las condiciones medioambientales que ofrezca el hospedero. Sin embargo, se desconoce la edad en que estas especies bacterianas comienzan a colonizar la cavidad bucal de los niños, como es el caso de Porphyromonas gingivalis, considerado uno de los periodontopatógenos más importantes. Esta especie posee múltiples factores de virulencia, entre los cuales se ha destacado la expresión de fimbrias, apéndices externos que juegan un rol determinante en la adhesión e invasión de los tejidos periodontales. Las fimbrias están constituidas por una subunidad proteica denominada fimbrilina (FimA), codificada por el gen fimA. Se han descrito 6 tipos de genes fimA en base a su secuencia de nucleótidos, codificando cada uno un tipo de fimbria diferente, las que se han asociado con distintos grados de salud y enfermedad periodontal. OBJETIVO: Investigar la presencia de Porphyromonas gingivalis, genotipos fimA-I, II, III y IV, en la microbiota bucal de niños de 4 a 8 años de edad. METODOLOGÍA: Se tomo muestras de hisopado de dorso lingual de 92 niños, de 4 a 8 años de edad, a quienes se les realizó un examen en búsqueda de signos clínicos de gingivitis y se distribuyeron según edad. La presencia de Porphyromonas gingivalis se investigó mediante cultivo microbiológico, pruebas bioquímicas y Reacción en Cadena de la Polimerasa (PCR). La detección de los genotipos fimA se llevó a cabo mediante PCR. RESULTADOS: Se detectó Porphyromonas gingivalis en el 11,95% de los niños (n=11), mediante cultivo y PCR, y 3 sujetos resultaron positivos a la presencia del genotipo fimA-IV de esta especie. Los 8 sujetos restantes no presentaron ninguno de los otros genotipos analizados en este estudio. CONCLUSIONES: Porphyromonas gingivalis puede ser miembro de la microbiota comensal de niños de 4 a 8 años de edad. La detección del genotipo fimA-IV podría indicar una colonización preferencial a edades tempranas por parte de este genotipo, lo que ameritaría una revisión en el tiempo, para evaluar su permanencia, reemplazo o asociación con la aparición de patologías periodontales
48
Burgess, Nicola. "Quorum sensing and regulation of virulence gene expression in Porphyromonas gingivalis." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394845.
49
Maietta, Nathan. "Effect of pH on the transcriptional profile of Porphyromonas gingivalis W83." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2222.
Abstract:
Porphyromonas gingivalis, a gram-negative, anaerobic bacterium, is widely recognized as a causative agent for periodontal disease. Despite sequencing of the complete genome, no research exists examining gene regulation response in P. gingivalis to shifts in pH. Previous studies have shown that P. gingivalis is capable of surviving in the variety of micro- environmental niches found within the oral cavity, including basic and acidic pH conditions. However, the underlying mechanisms of this survival are not well understood. This study examined P. gingivalis by comparing bacteria shocked at three acidic to neutral pH conditions (5.5, 6.5 and 7.0) to bacteria vii shocked at pH 8.5. Using microarray to examine global gene expression, differential gene expression was identified in all conditions, with total genes differentially regulated ranging from 30 to almost 500 genes. Among these, genes for ammonia production, and cation gradients were found significantly up-regulated in acidic conditions, indicating a possible role in base creation and cation transport for survival of P. gingivalis in adverse pH conditions.
50
Singh, Amrita. "ROLE OF CAPSULE IN THE INTERACTION OF PORPHYROMONAS GINGIVALIS WITH HOST." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/140.
Abstract:
Periodontal disease is a chronic oral disease that is triggered by bacteria. One of these bacteria is Porphyromonas gingivalis. Some strains of P. gingivalis produce capsule, however, so far the role of capsule in the interactions with host cells in P. gingivalis is not well understood. Here, we investigated the contribution of capsule to triggering host response as well as its protective role on bacterial internalization by host cells with subsequent killing. qRT-PCR analysis showed more upregulation of expression of various groups of genes in macrophages challenged with the non-capsulated strain than in those challenged with the capsulated one with ratios as high as 8.4:1. Cytokine quantification of IL-6 using ELISA indicated that the non-capsulated strain produced more IL-6 in macrophages at 1 hr post-infection and drastically more at 8 hrs post-infection than the capsulated strain with a 4-fold difference. Maturation markers were induced at two fold higher rate in dendritic cell challenged with the non-capsulated strain at 4 hrs compared to dendritic cells challenged with the capsulated strain. The rate of phagocytosis of the non-capsulated form of P. gingivalis by both dendritic cells and macrophages was 5-6 fold higher, respectively. On the contrary, survived of the non-capsulated P. gingivalis was drastically reduced compared to the capsulated strain. Our results indicate that the Porphyromonas gingivalis capsule plays an important role in aiding the evasion of the host immune system activation as well as promoting survival of the bacterium within host cells. As such it is a major virulence determinant of P. gingivalis.