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Introduction: The fimA-encoded fimbriae of the periodontal pathogen Porphyromonas gingivalis display genetic diversity. Type I fimbriated P. gingivalis (Pg-I) has been most widely studied at the molecular level, whereas Pg-II is the most frequent isolate from severe periodontitis. Methods: To investigate virulence differences between Types I and II fimbriae, we examined strains 33277 (Pg-I) and OMZ314 (Pg-II), reciprocal swap mutants (i.e. expressing the heterologous fimbrial type), and their respective FimA-deficient derivatives. These organisms were tested in a mouse periodontitis model and in interactions with mouse macrophages, a cell type that plays important roles in chronic infections. Results: Strain 33277 induced significantly more periodontal bone loss than OMZ314 and substitution of Type II fimbriae with Type I in OMZ314 resulted in a more virulent strain than the parent organism. However, the presence of Type II fimbriae was associated with increased proinflammatory and invasive activities in macrophages. Conclusion: The inverse relationship between proinflammatory potential and ability to cause experimental periodontitis may suggest that an aggressive phenotype could provoke a host response that would compromise the persistence of the pathogen. [ABSTRACT FROM AUTHOR]

Introduction: Porphyromonas gingivalis is a periodontal pathogen whose long fimbriae (FimA) are classified into six genotypes (types I–V and Ib) based on the diversity of the fimA genes. FimA variations were previously shown to be related to the onset and development of adult periodontitis in a general population, while FimA were recently found to be critical mediators of initial biofilm formation. However, it is unclear if FimA variations have effects on biofilm features. Here, we compare the characteristic structures of homotypic biofilms developed by P. gingivalis strains with different FimA types. Methods: Biofilms were formed on saliva-coated glass bottom wells in phosphate-buffered saline and their structures were analysed using confocal laser scanning microscopy. Furthermore, the biovolumes of the biofilms were quantified with a three-dimensional fluorophotometric method. Results: Biofilm structures formed by the six representative FimA-type strains apparently differed. Type I and Ib P. gingivalis formed biofilms with a dense basal monolayer and dispersed microcolonies, whereas those formed by types II, III and IV strains had markedly luxuriant biofilms filled with widely clumped and tall colonies, and their biovolumes were significantly greater than those of types I and Ib. These characteristic features were confirmed to be closely related to FimA type in assays that utilized fimA-substituted mutants from type I to II and those from type II to I. Conclusion: Our results suggest that FimA variations have effects on the structures of biofilms formed by P. gingivalis, which may be an important factor in the pathogenesis of periodontitis. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to assess the relationship between serum glycemic levels and subgingival microbial profile alteration following periodontal treatment in patients with type 2 diabetes mellitus. Methods: We studied 30 periodontitis patients with type 2 diabetes mellitus who received full-mouth subgingival debridement by analyzing their subgingival microbial profiles using a polymerase chain reaction method at baseline and various time-points for 12 months following treatment. Concurrently, probing pocket depth, bleeding on probing, and metabolic parameters, including glycated hemoglobin A1c (HbA1c), blood sugar level, C-reactive proteins, total cholesterol, triglyceride, and high-density and low-density lipoprotein cholesterol, were recorded. Results: Periodontal conditions were significantly improved after treatment, and the occurrence rates of periodontal bacterial species, including Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, and Prevotella intermedia, were also reduced. Interestingly, P. gingivalis was detected more frequently in subjects with increased HbA1c values after periodontal treatment than in those patients with decreased HbA1c values. Furthermore, P. gingivalis with type II fimbriae was detected only in HbA1c-increased subjects, while improvements in HbA1c values were observed only in subjects without type II clones. Conclusions: These results suggest that glycemic level in diabetes is affected by the persistence of P. gingivalis, especially clones with type II fimbriae, in periodontal pockets. [ABSTRACT FROM AUTHOR]

Background/aims: Porphyromonas gingivalis is a periodontal pathogen whose fimbriae are classified into six genotypes (types I–V and Ib) based on the diversity of the fimA genes encoding the fimbrial subunits. Accumulated evidence suggests that P. gingivalis strains with type II fimbriae are more virulent as compared to those with other types. However, it is unknown if strong virulence is uniformly conserved among clones with type II fimbriae. In the present study, we compared infectious inflammatory changes in clinical isolates of P. gingivalis with type II fimbriae using a mouse abscess model to examine their pathogenic heterogeneity and heterogeneity-related factors. Methods: Suspensions of nine different clinical isolates with type II fimbriae were subcutaneously injected into female BALB/c mice and inflammatory parameters, such as serum sialic acid concentration, were compared. Results: Many of the type II fimbrial isolates caused severe inflammation in the mice, though some were less causative, as was the control strain ATCC 33277 (type I fimbria strain). These results showed that pathogenic heterogeneity exists among P. gingivalis clones with type II fimbriae. Further, the heterogeneity-related factors of P. gingivalis strains were analyzed and the pathogenic potentials showed positive relationships to gingipain activities and invasive efficiency but not to hydrophobicity or autoaggregation. In addition, invasive efficiency was related to the activities of gingipains that were extracellularly secreted. Conclusion: These results suggest that pathogenic heterogeneity has relationships with the invasive and proteolytic activities of P. gingivalis clones with type II fimbriae. [ABSTRACT FROM AUTHOR]

Background/aims: Streptococcus parasanguinis is a primary colonizer of the tooth surface. Its adhesion is mediated by the long fimbriae, which are composed of multiple subunits of a serine-rich glycoprotein, Fap1. Previous studies revealed that a chromosomal region located downstream of fap1 is involved in the secretion and glycosylation of Fap1. In this study, we investigated the role of a glycosylation-associated gene, gap3, in Fap1 biogenesis. Methods: A gap3 non-polar mutant was constructed by insertional inactivation. The phenotype of the mutant and the subcellular distribution of its products were investigated. The binding ability of the mutant was tested with saliva-coated hydroxyapatite (SHA). Electron microscopy was used to observe the morphological changes on the mutant cell surface. Confocal microscopy was utilized to determine biofilm formation ability. Results: The gap3 mutant produced a partially glycosylated Fap1 precursor, that was less stable than mature Fap1. The Fap1 precursor was distributed in all subcellular fractions including the cell surface and culture medium although in decreased amounts. These data suggest a role for Gap3 in Fap1 glycosylation as well as a link between glycosylation and secretion of Fap1. The gap3 mutant had reduced binding to saliva-coated hydroxyapatite. Electron microscopy revealed that the gap3 mutant had lost its long fimbriae. Biofilm formation was also inhibited by the gap3 mutation. Fewer gap3 mutant cells adhered to the biofilm surface and microcolony formation was decreased. Conclusion: Gap3 is required for the complete glycosylation and secretion of Fap1, which is important for fimbrial assembly, bacterial adhesion, and in vitro biofilm formation. [ABSTRACT FROM AUTHOR]

Vitkov L, Krautgartner WD, Hannig M. Bacterial internalization in periodontitis. Oral Microbiol Immunol 2005: 20: 317–321.© Blackwell Munksgaard, 2005. Bacterial invasion of host epithelial cells plays an important role in the pathogenesis of periodontitis; however, the exact mechanism of the invasion has not been investigated. Pocket epithelium biopsies in periodontitis were analysed via scanning and transmission electron microscopy using ultra-histochemical staining with ruthenium red for glycocalyx visualization. We demonstrated that oral bacteria adhered via fimbriae-mediated adhesion only. The bacterial internalization in periodontitis was marked by the hallmark of the fimbriae-induced zipper mechanism – the phagocytic cup formation – but we found no sign of the trigger mechanism of internalization. In addition, we frequently observed apoptosis in the phagocytizing epithelial cells. Fimbriae-mediated adhesion is a prerequisite for bacterial invasion in periodontitis. This occurs by the fimbriae-induced zipper mechanism of internalization. As internalization induces apoptosis, the subsequent exfoliation might play a significant role in the clearance of periodontal pathogens. [ABSTRACT FROM AUTHOR]

Streptococcus salivarius is divided into two serological subgroups that carry either fibrils or fimbriae. Although fimbriae have been observed on up to 50% of S. salivarius strains in the human oral cavity, no function has yet been assigned to them. To determine whether S. salivarius fimbriae have a role in adhesion, we examined the ability of S. salivarius to coaggregate with selected microorganisms involved in periodontal diseases. Our results show that S. salivarius coaggregated with Fusobacterium nucleatum , Porphyromonas gingivalis , and Prevotella intermedia . However, only fimbriated S. salivarius cells were able to coaggregate with P. intermedia , suggesting a specific role for these structures in the interaction. Heat treatment, sensitivity to sugars, amino acids, and EDTA, as well as protease treatment were also used to further characterize coaggregation between S. salivarius and periodontopathogens. [ABSTRACT FROM AUTHOR]

Fimbriae have been reported to play an important role in the adherence of Porphyromonas gingivalis to oral surfaces and possibly in triggering host responses. P. gingivalis ATCC 33277 has two distinctly different fimbriae expressed on the cell surface. The 67-kDa fimbriae differ in size and antigenicity from the earlier reported FimA, a major 41-kDa fimbrial component of P. gingivalis . Expression of the 67-kDa fimbriae on the cell surface of a fimA mutant was investigated by electron microscopy. The 67-kDa fimbrial protein was purified from the fimA mutant by sonication, precipitation, and chromatography on a DEAE Sepharose CL-6B column. The N-terminal amino acid sequence of the 67-kDa fimbrillin was distinct from that of the 41-kDa fimbrillin. Moreover, we have found that the 67-kDa fimbrial protein from P. gingivalis ATCC 33277 induced IL-1α, IL-β, IL-6 and TNFα cytokine expression in mouse peritoneal macrophages. These results suggest that P. gingivalis 67-kDa fimbriae may play a part in the inflammatory response during the development of periodontal diseases. [ABSTRACT FROM AUTHOR]

Inflamed oral mucosa biopsies from patients with thrush and high candidal density were observed in a transmission electron microscope (TEM) using ultra-histochemical staining with ruthenium red for glycocalyx visualization. Fimbriae comprising the glycocalyx and enabling yeast adhesion to epithelial cells were clearly visualized by ruthenium red. All internalized portions of the yeast walls were devoid of glycocalyx, indicating that the growing tips of the hyphae mechanically penetrated the host cells. The attachment of Candida occurred in two ways: by fimbria-mediated adhesion enabling colonization of the epithelial surface, and by invasion of the superficial epithelial cells via hyphae. As the interaction between adhesin receptors and adhesins stimulates the production of proinflammatory cytokines, Candida adhesion itself is assumed to induce mucosal inflammation. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis has been strongly implicated in the pathogenesis of human periodontitis. Fimbriae mediate adherence and colonization of the oral cavity by this organism and may, therefore, have potential for use as antigen in an anti–P. gingivalis vaccine. The purpose of our study was to determine whether P. gingivalis fimbriae have opsonic target sites and whether they are accessible on the cell surfaces and cross-reactive among P. gingivalis fimbrial types and serotypes. Rabbits were immunized with a vaccine. The antiserum reacted with a 43-kDa fimbrillin monomer and a 43-kDa component in whole-cell sonicates of P. gingivalis 33277, but it showed only very weak reactivity in the 43-kDa region of Western blots of a whole-cell sonicate of strain DPG3, a mutant that does not express functional fimbriae. The antibody enhanced chemiluminescence approximately six-fold relative to preimmune serum values and significantly enhanced phagocytosis and killing of P. gingivalis 33277 by human polymorphonuclear leukocytes. Peak opsonic activity was observed at week 6 followed by a plateau that remained until week 16. The fimbria-deficient mutant DPG3 did not bind antifimbrial antibody and was not opsonized, whereas strain 381, the parent of the mutant, was opsonized. The specific antibody bound to and opsonized P. gingivalis strains 33277 and 381 (fimbria type I) but not W50, A7A-1-28, 9-14K-1 or FAY-19M-1 (fimbrial types II–V). Specific antibody bound to strain 2561 (fimbrial type I) but, as assessed by chemiluminescence, did not opsonize it. While fimbriae have opsonic target sites that are accessible on P. gingivalis cell surfaces, the relevant opsonic target sites do not appear to be shared across serotypes or fimbrial types. Thus, a vaccine containing, as antigen, fimbrial protein from a single P. gingivalis strain would likely be ineffective against infections by P. gingivalis strains expressing other fimbrial types. [ABSTRACT FROM AUTHOR]

We studied the genetic control of porphyromonas gingivalis fimbriae response. Inbred mice with different H-2 haplotypes and/or different genetic backgrounds were inoculated with viable P. gingivalis 381 cells and tested for fimbria-specific T cell responses in vivo (delayed-type hypersensitivity). H-2d mice showed a strong footpad response, whereas H-2b mice showed a weak response to fimbriae from P. gingivalis. Similar evidence of genetic control was obtained with an enzyme-linked immunosorbent assay for the detection of IgG antibody in inbred mice (BALB/c, C3H/HeN and C57BL/6). Several immunoglobulin G (IgG) subclass responses were associated with H-2 in these B10 congenic mice. However, quantification of IgG antibody to fimbriae was not controlled by H-2 in B10 congenic mice. The results indicate that, in mice, the responsiveness to fimbriae of P. gingivalis can be controlled by several genes, including the H-2 complex. C3H/HeN mice were inoculated with the fimbriae intravenously, and the expression of surface antigens on spleen T cells was measured in a fluorescent antibody cell sorter. Stimulation by fimbriae resulted in a changed expression of surface antigens on T cells. Thus, the fimbriae can induce T cell activation. [ABSTRACT FROM AUTHOR]

The cell-adherent ability of 6 strains of Porphyromonas gingivalis (381, ATCC 33277, SU63, KDI, W50 and W83) was compared by using radiolabeled bacterial cells and human gingival fibroblasts (Gin 1), human periodontal ligament fibroblasts (HPLF) and human epithelial cells (Ca9-22) that had been grown on collagen beads. The cell-adherent activity of these organisms varied among strains; P. gingivalis strains 381, ATCC 33277 and SU63 bound to the target cells at a range of 14% to 72%, but the other 3 strains (KD1, W50 and W83) were scarcely bound (0.6% to 3.5%). On the other hand, whole bacterial cells and culture supernatants of all strains showed distinct hemagglutinating activity. The 3 strains showing high cell-adherent activity were hydrophobic and the other strains showing less activity were relatively hydrophilic. Furthermore, a number of peritrichous fimbriae were found on the surface of P. gingivalis to strains 381, ATCC 33277 and SU63, which showed high adherent activity, whereas, fimbriae on the other 3 strains showing low adherent activity were barely apparent. Therefore, it was assumed that the cell-adherent activity of P. gingivalis was related to the hydrophobicity of the cell surface, which was related to the number of fimbriae. [ABSTRACT FROM AUTHOR]

The ability of low-frequency (200 Hz) acoustic energy to reduce the adherence of Actinomyces viscosus T14V to saliva-treated hydroxyapatite (SHA) disks was studied. An acoustic pressure range between 0 and 65 kPa and exposure durations between 0 and 8 mm were used to study the levels necessary to significantly alter adherence. The effects of acoustic exposure on both bacteria in liquid and bacteria already adhering to SHA disks were studied. A modified enzyme-linked immuno- sorbent assay was used to assess bacterial adherence. For bacterial suspensions exposed prior to addition to SHA disks, it was found that reductions in adherence were greater for lower bacterial concentrations. Exposure of bacteria already adhering to SHA disks resulted in a decrease in adherence that was independent of the bacterial concentration and linearly related to the logarithm of the exposure duration. In addition to affecting adherence, acoustic energy also dispersed bacterial aggregates. Our results support the concept that low-frequency sonic energy applied orally may be of therapeutic value in reducing adherence and colonization of the teeth by plaque bacteria. [ABSTRACT FROM AUTHOR]

The nucleotide sequence of the chromosomal DNA, upstream of Actinomyces naeslundii T14V fimbrial gene fimA, was determined. One open reading frame (orf977) encoding 977 amino acids was found, preceded by a gene homologous to elongation factor TU. Database searches revealed that Orf977 was homologous to CshA, a Streptococcus gordonii protein involved in cell adhesion. Previous studies had already determined two genes in the type 2 fimbrial gene cluster of A. naeslundii T14V: the structural subunit fimA, and orf365 with unknown function, followed by ribosomal genes. This study completes the type 2 fimbrial gene cluster sequence. [ABSTRACT FROM AUTHOR]