Thesis (Ph.D.)--Boston University, Henry M. Goldman School of Dental Medicine. / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Porphyromonas gingivalis , a Gram-negative anaerobic pathogen of periodontal diseases, requires iron in the form of heme (a term used to denote either the ferrous or ferric form of iron protoporphyrin IX) for growth. P. gingivalis is capable of utilizing a broad range of heme-containing compounds such as hemoglobin, hemoglobin-bound haptoglobin, hemin-bound hemopexin and hemin-saturated serum. Heme and hemoglobin utilization in P. gingivalis requires the participation of an outer membrane protein HmuR (heme utilization receptor), as well as cysteine proteinase gingipains (Lysine-specific gingipain Kgp and Arginine specific gingipains Rgps). However, the specific mechanisms utilized for heme acquisition are poorly understood. In this study, the role of HmuR in heme utilization was characterized in both E. coli and P. gingivalis . Molecular interaction between HmuR and hemin/hemoproteins was also characterized by construction and analysis of HmuR site-directed mutants. Our results support the direct role of HmuR in heme utilization. Hemoprotein utilization in P. gingivalis requires the participation of HmuR conserved residues. The HmuR residues 95 and 434, as well as the NPDL motif, seem to be involved in whole cell binding of hemoproteins; while the YRAP motif does not. All these residues seem essential for serum hemoprotein utilization. Analyses of HmuR by homology modeling provided a structural basis for functional analysis and supported the results from mutagenesis studies. In addition, expression of the hmuR, kgp and rgpA genes in response to different heme sources was also examined. We found that expression of the hmuR gene was negatively regulated by heme, while expression of the kgp and rgpA genes seemed to be regulated by growth phase. These different regulatory mechanisms, as well as the coordinate expression between HmuR and gingipains, indicate a complementary regulation mechanism for optimal heme utilization in P. gingivalis. / 2031-01-01

Mounting evidence has pointed to associations between Alzheimer's disease (AD) and dysbiotic microbiota in the oral cavity and GI tract. However, no studies have compared the role of specific oral and GI-tract pathogens in the development of AD or the roles inflammation severity and sex may play. We compared the effect of chronic exposure to two doses of lipopolysaccharides (LPS) from a periodontal pathogen, Porphyromonas gingivalis, and a GI-tract pathogen, Escherichia coli, on neuroinflammation, cognition, and AD-like pathology. P. gingivalis-LPS, E. coli-LPS, or endotoxin-free PBS was continuously subcutaneously administered to adult male and female C57BL/6 mice for 28 days via osmotic pumps at 250 µg/kg/day (low-dose) or 500 µg/kg/day (high-dose). After 21 days, spatial learning and reference memory were assessed using the Morris Water Maze (MWM) and Y-Maze. After 28 days of LPS treatment, levels of proinflammatory cytokines, TNF-α and IL-β, in serum and brain tissue were measured by ELISA. Markers of AD pathology and inflammation were detected in situ using immunohistochemistry (IHC) in paraffin-embedded brain sections. Western blot (WB) analysis was used to compare the expression of Toll-Like Receptors (TLR) 2 and 4 in brain, bone, liver, and kidney tissues. Sustained exposure to high-dose, but not low-dose, P. gingivalis-LPS or E. coli-LPS significantly impaired cognition in male mice only. P. gingivalis-LPS triggered worse cognitive impairment and neuroinflammation, whereas E. coli-LPS caused more pronounced serum inflammation. IHC analysis revealed that P. gingivalis-LPS-treated male mice had increased amyloid precursor protein and hyperphosphorylated tau protein in both the hippocampus and neocortex, while E. coli-LPS treatment had a less prominent effect. P. gingivalis-LPS also induced a greater degree of astrogliosis. The mechanisms underlying these observations may be related to differential TLR2 and TLR4 expression, as WB analysis showed TLR2 was predominantly expressed in the brain while TLR4 was constitutively expressed in both the brain and peripheral tissues. Overall, P. gingivalis-LPS treatment triggered more prominent neuroinflammation, cognitive impairment, and AD-like pathological brain changes than E. coli-LPS treatment. Moreover, these phenotypes were dose-dependent and sex-dependent. In conclusion, chronic periodontitis may be a significant risk factor for AD, and this relationship warrants further investigation.

No description available.

Les parodontites sont des maladies inflammatoires de nature infectieuse affectant les tissus de soutien de la dent. La présence de bactéries parodontopathogènes dans le sillon gingival représente le facteur étiologique primaire responsable du déclenchement de la parodontite. La réponse immunitaire de l'hôte face à l'agression par ces parodontopathogènes détermine l'évolution de la maladie vers la destruction tissulaire ou la guérison. En effet, la stimulation des cellules immunitaires et mucosales par les bactéries et leurs facteurs de virulence engendre une forte production de médiateurs inflammatoires et de métalloprotéinases matricielles. Ce phénomène a pour conséquence d'activer diverses voies de dégradation tissulaire et osseuse. Le système du complément est l'un des éléments importants de la réaction immunitaire puisqu'il permet l'élimination de microorganismes pathogènes. Pour éviter un effet néfaste du système du complément, les cellules de mammifères expriment à leur surface des protéines régulatrices du complément (CRPs) qui neutralisent les composantes du complément. Le but de cette étude était d'investiguer la capacité des bactéries parodontopathogènes à déjouer le système de défense de l'hôte et/ou de contribuer à l'inflammation et à la destruction tissulaire, en interagissant avec les CRPs. D'une part, nous avons démontré que Porphyromonas gingivalis, une bactérie anaérobie stricte à Gram négatif fortement associée à la parodontite chronique, peut induire le largage de la protéine CD46 de la surface des cellules épithéliales buccales. Une fois détachée des cellules, cette protéine est dégradée par les enzymes protéolytiques sécrétées par P. gingivalis. D'autre part, Fasobacterhim nucleatum, une bactérie cohabitant avec P. gingivalis, a montré une capacité à lier à sa surface la protéine CD46 soluble. F. nucleatum couvert de la protéine CD46 s'est avéré capable d'induire une sécrétion de cytokines proinflammatoires par les cellules épithéliales. Enfin, une stimulation des cellules épithéliales par le lipopolysaccharide des parodontopathogènes a révélé une surexpression des gènes codant pour les CRPs, dont CD46, CD55 et CD59. L'ensemble de ces résultats ont mené à une meilleure compréhension des interactions des interactions des bactéries parodontopathogènes avec le système du complément et des mécanismes contribuant à l'inflammation et à la destruction tissulaire.

Dans ce projet, la capacité des polyphénols du thé vert à moduler l’expression de certains gènes chez Porphyromonas gingivalis, le principal agent étiologique de la parodontite chronique, a été évaluée. Une analyse par PCR quantitative a démontré qu’à des concentrations sous-inhibitrices, l’extrait de thé vert ainsi que l’épigallocatéchine-3-gallate (EGCG) réduisent à différents degrés le niveau d’expression de gènes codant pour d’importants facteurs de virulence chez P. gingivalis. Ces facteurs participent notamment à la colonisation, l’acquisition des nutriments et la destruction tissulaire. De plus, les deux composés ont augmenté le niveau d’expression du gène codant pour la protéine de résistance au stress HtrA chez P. gingivalis. Les résultats de cette étude suggèrent que le thé vert et l’EGCG pourraient contribuer à réduire la virulence de P. gingivalis, supportant ainsi une potentielle utilisation pour la prévention et le traitement de la parodontite.

As doenças periodontais são infecções locais que apresentam morbidade e têm sido relacionadas com outras doenças ou complicações sistêmicas. Pacientes tabagistas apresentam taxas elevadas e maior predisposição às doenças periodontais severas e avançadas. A administração sistêmica de antibióticos, particularmente metronidazol (M) e amoxicilina (A), associados ao tratamento periodontal mecânico (raspagem e alisamento radiculares - RAR) tem sido amplamente estudada frente às doenças periodontais crônicas. Porém, pouco tem sido esclarecido referente aos efeitos desses tratamentos sobre Porphyromonas gingivalis e seus genótipos. Os objetivos deste trabalho foram: avaliar os efeitos clínicos (profundidade a sondagem - PS, nível de inserção clínica - NIC, índice de placa - IP, sangramento gengival - SG, sangramento à sondagem SS, e supuração - SUP) e microbiológicos (referente à presença de P. gingivalis e seus genótipos fimA II, fimA IV e ragB) após 180 dias do tratamento periodontal mecânico (RAR) associado à administração sistêmica de antibióticos (RAR+M+A), comparados ao tratamento periodontal mecânico (RAR), utilizando-se o PCR convencional (primers específicos para 16S rRNA); e relacionar a presença de P. gingivalis e seus genótipos fimA II, fimA IV e ragB com a profundidade de sondagem (PS) em pacientes fumantes com periodontite crônica. Foram avaliadas 167 amostras oriundas de sítios de 20 sujeitos tratados com RAR (n=11) e RAR + M + A (n=9), no exame inicial e 180 dias após a terapia. Parâmetros clínicos (PS, NIC, IP, SG, SS e SUP) e coletas microbiológicas foram mensuradas em ambos tempos. A detecção da freqüência de P. gingivalis foi realizada por PCR convencional, bem como para os genótipos fimA II, fimA IV e ragB. Não houve diferença estatisticamente significante entre o tratamento periodontal mecânico associado à administração sistêmica de antibióticos (RAR+M+A) e o tratamento periodontal mecânico (RAR), nos pacientes fumantes, em relação à detecção de P. gingivalis. O grupo RAR apresentou-se mais efetivo (estatisticamente significante) na redução de prevalência do genótipo ragB, em comparação ao grupo RAR+M+A, após 180 dias do tratamento. Não foi observada relação estatisticamente significante entre a prevalência de P. gingivalis e dos genótipos fimA II, fimA IV e ragB com a PS no exame inicial. / Periodontal diseases are local infections that present morbidity and have been relation with others systemic diseases or complications. Smoking patients present high levels and bigger predisposition to the severe and advanced periodontal diseases. The systemic administration of antibiotics, mainly metronidazole (M) and amoxicillin (A), associated to the mechanical periodontal treatment (scaling and root planing - SRP) has been largely researched referring to the chronic periodontal diseases. However, not much has been cleared up referring to the effects of those treatments about Porphyromonas gingivalis and its genotypes. The purpose of this research was to evaluate the clinical effects (depth probing - DP, clinical attachment level - CAL, plaque index - PI, gingival bleeding - GB, bleeding on probing - BOP, and supuration - SUP) and microbiological (referring to the presence of P. gingivalis and its genotypes fimA II, fimA IV and ragB) after 180 days of the mechanical periodontal treatment (SRP) associated to the systemic administration of antibiotic (SRP+M+A), compared to the mechanical periodontal treatment (SRP) in smoking patients with chronic periodontitis, by using the conventional PCR (specific primers to the 16S rRNA); to associate the P. gingivalis presence and its genotypes fimA II, fimA IV and ragB with depth probing (DP) of the researched population. 167 samples from the sites of 20 subjects treated with SRP (n=11) and SRP+M+A (n=9) have been evaluated, at the baseline and 180 days after the therapy. Clinical parameters (DP, CAL, PI, GB, BOP and SUP) and microbiological samples were evaluated in both moments. The detection of P. gingivalis frequence was made by using conventional PCR, and also to the genotypes fimA II, fimA IV and ragB. There was no statistically significative difference between the mechanical periodontal treatment associated to the systemic administration of antibiotics (SRP+M+A) and the mechanical periodontal treatment (SRP), in the smoking patients, related to the detection of the P. gingivalis. The SRP group showed more effective (statiscally significative) on the reduction of the genotype ragB prevalence, comparing to the SRP+M+A group, after 180 days of therapy. No statistically significative relation between the prevalence of P. gingivalis and its genotypes fimA II, fimA IV e ragB with DP at the baseline have been observed.

O objetivo do presente trabalho foi investigar o efeito da hiperglicemia na alteração da homeostase imunológica mediada pelas células dendríticas (DCs) em resposta a uma bacteremia induzida por raspagem e alisamento radicular (RAR) em indivíduos com periodontite crônica generalizada (GCP). Foram selecionados 60 indivíduos igualmente divididos em quatro grupos: controles normoglicêmicos saudáveis, normoglicêmicos com GCP (NG+GCP), pré-diabéticos com GCP (PD+GCP) e diabéticos tipo 2 com GCP (T2DM+GCP). Os indivíduos com GCP receberam RAR, o que induziu uma bacteremia aguda e os controles saudáveis receberam apenas raspagem supragengival. Todos os participantes foram avaliados no início do estudo, 24hs, 1 mês e 3 meses após a raspagem. A frequência de células dendríticas mielóides (mDCs) CD1c+, mDCs CD141+, células dendríticas plasmocitoides (pDCs) CD303+ e a expressão dos receptores CCR6 (presente em altos níveis em células dendríticas imaturas) e CCR7 (presente em altos níveis em células dendríticas maduras) foram avaliados por citometria de fluxo. Foi utilizada técnica de PCR em tempo real para investigar a presença de Porphyromonas gingivalis (P. gingivalis) no biofilme e abrigada pelas DCs. No início do estudo, os indivíduos hiperglicêmicos com GCP tinham níveis de DCs significativamente mais baixos do que os indivíduos normoglicêmicos com ou sem GCP. Após a bacteremia induzida por RAR, observou-se um aumento significativo nos níveis de CD1c+ e CD1c+CCR6+ em todos os grupos com GCP, independentemente do status de glicemia, e esses níveis voltaram aos níveis basais após 1 mês. Em comparação com o grupo NG+GCP, o grupo T2DM+GCP apresentou níveis significativamente mais baixos de DCs ao longo de todos os períodos experimentais. Não foram observadas alterações significativas para CD303+, CD1c+ CCR7+ e CD141+ em resposta à bacteremia; CD303+ e CD141+ foram significativamente mais baixos para T2DM+GCP comparado ao grupo NG+GCP ao longo do estudo. A quantidade de P. gingivalis nas DCs estava aumentada no grupo NG+GCP no início do estudo e após 24h da RAR comparado ao controle, mas não nos grupos hiperglicêmicos. Os resultados premitiram concluir que a hiperglicemia parece afetar negativamente a presença de mDCs e pDCs no sangue periférico e a abilidade dessas células em capturar P. gingivalis. Considerando que a magnitude da expansão de mDCs em resposta a um desafio bacteriano foi semelhante, os indivíduos hiperglicêmicos permaneceram imunocomprometidos em comparação com indivíduos normoglicêmicos. / The objective of this study was to investigate the effect of hyperglycemia in the disruption of dendritic cells (DCs) mediated immune homeostasis in response to an acute short-term bacteremia in subjects with generalized chronic periodontitis (GCP). Sixty subjects equally divided into four groups were selected: normoglycemic healthy controls, normoglycemics with GCP (NG+GCP), pre-diabetics with GCP (PD+GCP), and type-2 diabetes mellitus with GCP (T2DM+GCP). Subjects with GCP received full-mouth scaling and root planning (SRP), which induced an acute bacteremia, while healthy controls received only a prophylaxis. All participants were examined at baseline, 24hs after SRP, 1 month, and 3 months. The frequency of CD1c+ myeloid DCs (mDCs), CD141+ mDCs, CD303+ plasmacytoid DCs (pDCs) and their expression of immature DC tissue homing receptor CCR6+ and secondary lymphoid organ (SLO)-homing receptor CCR7+ were analyzed by flow cytometry. The presence of Porphyromonas gingivalis (P. gingivalis) mRNA within blood DCs was analyzed by real time PCR. At baseline, hyperglycemic subjects with GCP showed lower DC levels than normoglycemic subjects with or without GCP. After SRP induced bacteremia, a significant increase in CD1c+ and CD1c+CCR6+ levels was observed in all GCP groups, which returned to baseline levels after 1 month. Compared to NG+GCP, T2DM+GCP had significantly lower levels of DCs throughout the experimental periods. No significant changes were observed for CD303+, CD1c+CCR7+ and CD141+ in response to the bacteremia; CD303+ and CD141+ were significantly lower for T2DM+GCP than NG+GCP throughout the study. P. gingivalis carriage state of DCs was increased in the NG+GCP group, but not in the hyperglycemic groups. Hyperglycemia appears to negatively affect the pool of mDCs and pDCs and the ability of blood DCs to captures bacteremic P. gingivalis. Whereas the magnitude of mDCs expansion in response to a bacterial challenge was similar, hyperglycemic subjects remained immunocompromised in comparison to normoglycemic subjects.

Porphyromonas gingivalis é um dos principais organismos associados à periodontite crônica e apresenta intensa diversidade, que poderia refletir em sua virulência. A maioria dos estudos sobre a virulência de P. gingivalis foi realizada com cepas de referência, e pouco se conhece sobre este aspecto em isolados clínicos. A capacidade de indução de abscessos difusos em modelos animais experimentais parece estar associada a cepas capsuladas, enquanto a expressão de fímbrias e a capacidade de internalização em células epiteliais não fagocíticas, foram relacionadas à cepa não capsulada. Em P. gingivalis, o lócus de biossíntese do polissacarídeo capsular (BPC) apresenta características de ter sido adquirido por transferência horizontal de genes. O objetivo do presente estudo foi testar a hipótese de que a estrutura populacional de P. gingivalis relaciona-se com a variabilidade do lócus BPC e características fenotípicas como produção de cápsula e hidrofobicidade. Foram analisadas 28 cepas de P. gingivalis pertencentes aos 5 genótipos fimA quanto a, presença da cápsula por microscopia óptica, hidrofobicidade e detecção de genes do lócus BPC por PCR. A análise filogenética foi realizada por tipagem através de seqüenciamento de genes housekeeping (multilocus sequence typing, MLST). Dezesseis entre 28 amostras estudadas apresentaram cápsula, e não foram detectadas diferenças na hidrofobicidade dos isolados clínicos capsulados e não capsulados. O gene pg0106 foi detectado por PCR em 78% das amostras capsuladas e em 80% das amostras não capsuladas, enquanto pg0111 foi detectado em apenas 25% de amostras capsuladas. Apenas um isolado clínico e a amostra padrão W83 foram classificados como K1, por apresentarem o gene pg0118. Através do MLST foi possível identificar grande variabilidade entre as amostras de P.gingivalis. Foi observada relação entre STs e o tipo fimA ou hidrofobicidade, mas nenhum cluster foi associado à presença da cápsula ou aos genes do lócus de biossíntese do polissacarídeo capsular. Os dados indicam associação entre o lócus BPC e produção de cápsula, porém a diversidade deste lócus parece ser maior do que a relatada na literatura. O lócus BPC e a produção de cápsula não se relacionam com a origem filogenética da cepa, indicando a intensa recombinação que ocorre em P. gingivalis. / Porphyromonas gingivalis is one of main organisms associated with chronic periodontitis and is largely diverse, which could reflect in its virulence. Most studies on the virulence of P.gingivalis were performed with reference strains, and little is known about this aspect in clinical isolates. The ability to induce diffuse abscesses in experimental animal models seems to be associated with encapsulated strains, while expression of fimbriae and the ability to internalize into non phagocytic epithelial cells were related to noncapsulated strains. In P.gingivalis, the locus of biosynthesis of the capsular polysaccharide (GP) has characteristics of having been acquired by horizontal gene transfer. This study aimed to test the hypothesis that the structure population of P.gingivalis is related to the variability of the GPC locus and phenotypic characteristics such as capsule production and hydrophobicity. 28 P.gingivalis isolates representing fimA genotypes were screened for presence of capsule by light microscopy, hydrophobic properties and detection of genes in the GPC locus by PCR. The phylogenetic analysis was performed by sequencing of housekeeping genes typing (multilocus sequence typing, MLST). Sixteen of 28 studied samples had capsule, and there were no differences in the hydrophobic properties of capsulated and non capsulated clinical isolates. The pg0106 gene was detected by PCR in 78% of capsulated isolates and in 80% of not capsulated while pg011 was detected in only 25% of encapsulated isolates. One clinical isolate and reference strain W83 were classified as K1, due to the presence of pg0118 gene. MLST detected large variations within the P.gingivalis population. MLST clustering analysis revealed a relation between sequence type (STs) and fimA genotype or hydrophobic property, but there was no association of STs with the presence of capsule or the genes encoding for the biosynthesis of capsular polysaccharide. The data indicated an association between GPC locus and capsule production but the diversity of this locus appeared to be greater than that reported in the literature. The GPC locus and capsule production were not related to the phylogenetic origin of the strain, indicating intense recombination in P. gingivalis.

P. gingivalis é um dos principais patógenos da doença periodontal, é encontrado em biofilmes orais com S. gordonii e P. intermedia e em células endoteliais da artéria coronária in vivo. P. gingivalis necessita de ferro em seu metabolismo e pode usar certas proteínas do hospedeiro como fontes deste íon em ambientes limitantes. Assim, este estudo investigou o papel dos genes PGN0741/PG0637 (receptor dependente de TonB) e PGN0531/PG1380 (fvW) de P. gingivalis na formação de biofilme em diferentes concentrações de ferro, em biofilmes mistos com S. gordonii e P. intermedia, e na adesão e invasão de células endoteliais da artéria coronária. Os resultados mostraram divergências no papel dos genes TonB e fvW na formação dos monobiofilmes e mistos e em diferentes concentrações de ferro, demonstrando uma relação cepa-dependente. Na adesão, fvW se mostrou importante para ambas cepas, mas na persistência apenas para P. gingivalis W83. Este trabalho enfatiza, assim, a necessidade do uso de mais de uma cepa de P. gingivalis no estudo do papel de genes em ensaios experimentais. / P. gingivalis is one of the major pathogens of periodontal diseases. It is found in oral biofilms associated with S. gordonii and P. intermedia, and inside of coronary artery endothelial cells in vivo. P. gingivalis requires iron for growth and can exploit iron-carrying proteins of the host as sources in limiting environments. Thus, this work aimed to study the role of genes PGN0741/PG0637 (TonB-dependent receptor) and PGN0531/PG1380 (fvW) of P. gingivalis in biofilm formation under different iron concentrations, in mixed biofilms with S. gordonii and P. intermedia, and in the adhesion and invasion of coronary artery endothelial cells. Our data showed discordance for the role of TonB and fvW in homo- and heterotypic biofilm formation and in different iron concentrations. The relevance of both genes was strain-dependent. Gene fvW was relevant for adhesion to endothelial cells, but only for strain W83 during persistence. Therefore, our study emphasizes the importance of using different strains for a better understanding of the role of genes in experimental assays.

O objetivo do presente trabalho foi investigar o efeito da hiperglicemia na alteração da homeostase imunológica mediada pelas células dendríticas (DCs) em resposta a uma bacteremia induzida por raspagem e alisamento radicular (RAR) em indivíduos com periodontite crônica generalizada (GCP). Foram selecionados 60 indivíduos igualmente divididos em quatro grupos: controles normoglicêmicos saudáveis, normoglicêmicos com GCP (NG+GCP), pré-diabéticos com GCP (PD+GCP) e diabéticos tipo 2 com GCP (T2DM+GCP). Os indivíduos com GCP receberam RAR, o que induziu uma bacteremia aguda e os controles saudáveis receberam apenas raspagem supragengival. Todos os participantes foram avaliados no início do estudo, 24hs, 1 mês e 3 meses após a raspagem. A frequência de células dendríticas mielóides (mDCs) CD1c+, mDCs CD141+, células dendríticas plasmocitoides (pDCs) CD303+ e a expressão dos receptores CCR6 (presente em altos níveis em células dendríticas imaturas) e CCR7 (presente em altos níveis em células dendríticas maduras) foram avaliados por citometria de fluxo. Foi utilizada técnica de PCR em tempo real para investigar a presença de Porphyromonas gingivalis (P. gingivalis) no biofilme e abrigada pelas DCs. No início do estudo, os indivíduos hiperglicêmicos com GCP tinham níveis de DCs significativamente mais baixos do que os indivíduos normoglicêmicos com ou sem GCP. Após a bacteremia induzida por RAR, observou-se um aumento significativo nos níveis de CD1c+ e CD1c+CCR6+ em todos os grupos com GCP, independentemente do status de glicemia, e esses níveis voltaram aos níveis basais após 1 mês. Em comparação com o grupo NG+GCP, o grupo T2DM+GCP apresentou níveis significativamente mais baixos de DCs ao longo de todos os períodos experimentais. Não foram observadas alterações significativas para CD303+, CD1c+ CCR7+ e CD141+ em resposta à bacteremia; CD303+ e CD141+ foram significativamente mais baixos para T2DM+GCP comparado ao grupo NG+GCP ao longo do estudo. A quantidade de P. gingivalis nas DCs estava aumentada no grupo NG+GCP no início do estudo e após 24h da RAR comparado ao controle, mas não nos grupos hiperglicêmicos. Os resultados premitiram concluir que a hiperglicemia parece afetar negativamente a presença de mDCs e pDCs no sangue periférico e a abilidade dessas células em capturar P. gingivalis. Considerando que a magnitude da expansão de mDCs em resposta a um desafio bacteriano foi semelhante, os indivíduos hiperglicêmicos permaneceram imunocomprometidos em comparação com indivíduos normoglicêmicos. / The objective of this study was to investigate the effect of hyperglycemia in the disruption of dendritic cells (DCs) mediated immune homeostasis in response to an acute short-term bacteremia in subjects with generalized chronic periodontitis (GCP). Sixty subjects equally divided into four groups were selected: normoglycemic healthy controls, normoglycemics with GCP (NG+GCP), pre-diabetics with GCP (PD+GCP), and type-2 diabetes mellitus with GCP (T2DM+GCP). Subjects with GCP received full-mouth scaling and root planning (SRP), which induced an acute bacteremia, while healthy controls received only a prophylaxis. All participants were examined at baseline, 24hs after SRP, 1 month, and 3 months. The frequency of CD1c+ myeloid DCs (mDCs), CD141+ mDCs, CD303+ plasmacytoid DCs (pDCs) and their expression of immature DC tissue homing receptor CCR6+ and secondary lymphoid organ (SLO)-homing receptor CCR7+ were analyzed by flow cytometry. The presence of Porphyromonas gingivalis (P. gingivalis) mRNA within blood DCs was analyzed by real time PCR. At baseline, hyperglycemic subjects with GCP showed lower DC levels than normoglycemic subjects with or without GCP. After SRP induced bacteremia, a significant increase in CD1c+ and CD1c+CCR6+ levels was observed in all GCP groups, which returned to baseline levels after 1 month. Compared to NG+GCP, T2DM+GCP had significantly lower levels of DCs throughout the experimental periods. No significant changes were observed for CD303+, CD1c+CCR7+ and CD141+ in response to the bacteremia; CD303+ and CD141+ were significantly lower for T2DM+GCP than NG+GCP throughout the study. P. gingivalis carriage state of DCs was increased in the NG+GCP group, but not in the hyperglycemic groups. Hyperglycemia appears to negatively affect the pool of mDCs and pDCs and the ability of blood DCs to captures bacteremic P. gingivalis. Whereas the magnitude of mDCs expansion in response to a bacterial challenge was similar, hyperglycemic subjects remained immunocompromised in comparison to normoglycemic subjects.