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Rudney JD, Chen R, Sedgewick GJ. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis are Components of a Polymicrobial Intracellular Flora within Human Buccal Cells. J Dent Res 2016; 84:59-63. [PMID: 15615877 DOI: 10.1177/154405910508400110] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Previously, we used in situ hybridization and confocal microscopy to detect the periodontal pathogens Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis within buccal epithelial cells taken directly from the mouth. This study tested the hypothesis that the intracellular flora of buccal cells is polymicrobial. Mixtures containing a red fluorescent universal probe paired with green fluorescent versions of either A. actinomycetemcomitans-, P. gingivalis-, or T. forsythensis-specific probes were hybridized with buccal cells collected from each of 38 healthy humans. We verified co-localization of probe pairs within cells by generating three-dimensional reconstructions. Intracellular bacteria were detected in every subject. Each cell that was labeled with a species-specific probe also contained bacteria recognized only by the universal probe. Bacteria labeled with specific probes often occupied smaller regions within larger masses of bacteria. Those findings suggest that future studies of invasion by oral bacteria may need to include microbial consortia.
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Affiliation(s)
- J D Rudney
- Department of Oral Science, School of Dentistry, University of Minnesota, Minneapolis, 55455, USA.
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Belibasakis G, Thurnheer T, Bostanci N. Porphyromonas gingivalis: a heartful oral pathogen? Virulence 2014; 5:463-4. [PMID: 24759693 PMCID: PMC4063808 DOI: 10.4161/viru.28930] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 04/16/2014] [Indexed: 12/17/2022] Open
Affiliation(s)
- Georgios Belibasakis
- Oral Microbiology and Immunology; Institute of Oral Biology; Center of Dental Medicine; University of Zürich; Zürich, Switzerland
| | - Thomas Thurnheer
- Oral Microbiology and Immunology; Institute of Oral Biology; Center of Dental Medicine; University of Zürich; Zürich, Switzerland
| | - Nagihan Bostanci
- Oral Translational Research; Institute of Oral Biology; Center of Dental Medicine; University of Zürich; Zürich, Switzerland
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Saito A, Kokubu E, Inagaki S, Imamura K, Kita D, Lamont RJ, Ishihara K. Porphyromonas gingivalis entry into gingival epithelial cells modulated by Fusobacterium nucleatum is dependent on lipid rafts. Microb Pathog 2012; 53:234-42. [PMID: 23034475 DOI: 10.1016/j.micpath.2012.08.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/20/2012] [Accepted: 08/21/2012] [Indexed: 11/29/2022]
Abstract
Host cell invasion by a major periodontal pathogen, Porphyromonas gingivalis, has been proposed as an important mechanism involved in host-pathogen interactions in periodontal and cardiovascular diseases. The present study sought to gain insight into the underlying mechanism(s) involved in previously demonstrated fusobacterial modulation of host cell invasion by P. gingivalis. An immortalized human gingival cell line Ca9-22 was dually infected with P. gingivalis ATCC 33277 and Fusobacterium nucleatum TDC 100, and intracellular invasion was assessed by scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). SEM observation showed that P. gingivalis and F. nucleatum formed consortia and were in the process of penetrating into Ca9-22 by 30-60 min after infection. In CSLM, Ca9-22 cells that contained both P. gingivalis and F. nucleatum were frequently observed after 2 h, although cells that contained exclusively P. gingivalis were also found. Infection by P. gingivalis and/or F. nucleatum revealed evident colocalization with a lipid raft marker, GM1-containing membrane microdomains. In an antibiotic protection assay, depletion of epithelial plasma membrane cholesterol resulted in a significant reduction of recovered P. gingivalis or F. nucleatum (∼33% of untreated control; p < 0.001). This inhibition was also confirmed by CSLM. Sequential infection experiments showed that timing of infection by each species could critically influence the invasion profile. Co-infection with F. nucleatum significantly enhanced host cell invasion by P. gingivalis 33277, its serine phophatase SerB mutant and complemented strains, suggesting that the SerB does not play a major role in this fusobacterial enhancement of P. gingivalis invasion. Thus, the interaction between F. nucleatum and host cells may be important in the fusobacterial enhancement of P. gingivalis invasion. Collectively, these results suggest that lipid raft-mediated process is at least one of the potential mechanisms involved in fusobacterium-modulated host cell invasion by P. gingivalis.
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Affiliation(s)
- Atsushi Saito
- Department of Periodontology, Tokyo Dental College, 1-2-2 Masago, Chiba 261-8502, Japan.
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Sun W, Wu J, Lin L, Huang Y, Chen Q, Ji Y. Porphyromonas gingivalisstimulates the release of nitric oxide by inducing expression of inducible nitric oxide synthases and inhibiting endothelial nitric oxide synthases. J Periodontal Res 2010; 45:381-8. [DOI: 10.1111/j.1600-0765.2009.01249.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Saito A, Inagaki S, Kimizuka R, Okuda K, Hosaka Y, Nakagawa T, Ishihara K. Fusobacterium nucleatum enhances invasion of human gingival epithelial and aortic endothelial cells by Porphyromonas gingivalis. ACTA ACUST UNITED AC 2009; 54:349-55. [PMID: 19049647 DOI: 10.1111/j.1574-695x.2008.00481.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Invasion by Porphyromonas gingivalis has been proposed as a possible mechanism of pathogenesis in periodontal and cardiovascular diseases. Porphyromonas gingivalis have direct access to the systemic circulation and endothelium in periodontitis patients by transient bacteremia. Periodontitis can be described as one of the predominant polymicrobial infections of humans. In the present study, P. gingivalis strains were tested for their ability to invade a human gingival epithelial cell line (Ca9-22) and human aortic endothelial cells in coinfection with Fusobacterium nucleatum using antibiotic protection assays. Coinfection with F. nucleatum resulted in 2-20-fold increase in the invasion of host cells by P. gingivalis strains. The invasive abilities of P. gingivalis strains were significantly greater when incubated with a F. nucleatum clinical isolate (which possesses strong biofilm-forming ability), than when incubated with a F. nucleatum-type strain. In inhibition assays with metabolic inhibitors, a difference in inhibition profiles was observed between mono- and polymicrobial infections. Collectively, our results suggest that F. nucleatum facilitates invasion of host cells by P. gingivalis. Investigations of polymicrobial infection of host cells should improve our understanding of the role of P. gingivalis in periodontal infection and proatherogenic mechanisms.
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Affiliation(s)
- Atsushi Saito
- Oral Health Science Center, Tokyo Dental College, Chiba, Japan.
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Colombo AV, da Silva CM, Haffajee A, Colombo APV. Identification of intracellular oral species within human crevicular epithelial cells from subjects with chronic periodontitis by fluorescence in situ hybridization. J Periodontal Res 2007; 42:236-43. [PMID: 17451543 DOI: 10.1111/j.1600-0765.2006.00938.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND AND OBJECTIVE Interactions between oral bacteria and gingival epithelial cells play an important role in the pathogenesis of periodontal diseases. This study used in situ hybridization with 16 rRNA probes and confocal microscopy to detect the periodontal pathogens Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Tannerella forsythia, and Treponema denticola within epithelial cells from periodontal pockets, gingival crevice, and buccal mucosa collected from subjects with chronic periodontitis (n = 14) and good periodontal health (n = 8). MATERIAL AND METHODS Each green fluorescent species-specific and universal probe was hybridized with all 58 epithelial samples from the 22 patients. The samples were observed by confocal microscopy to confirm the intracellular localization of oral species of bacteria. The mean frequency of detection and number of intracellular bacteria per epithelial cell were computed for each sample. RESULTS The frequency of cells with internalized bacteria was higher in samples from the gingival crevice than in samples from the oral mucosa. Epithelial cells from all subjects harbored intracellular bacteria; however, patients with periodontitis presented significantly higher counts of bacteria per cell than periodontally healthy individuals (p < 0.05). Periodontal pathogens showed a trend to be detected in higher numbers in epithelial cells from periodontitis patients. In particular, T. forsythia and T. denticola were significantly more prevalent in periodontal pocket cells than healthy sulci and buccal cell samples in the periodontitis group (p < 0.05). CONCLUSION Those findings indicate that crevicular and buccal cells present internalized bacteria, regardless of periodontal status. However, higher bacterial loads are detected in cells from subjects with periodontitis.
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Affiliation(s)
- A V Colombo
- Institute of Microbiology, Department of Medical Microbiology, Federal University of Rio de Janeiro, Brazil.
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Mans JJ, Baker HV, Oda D, Lamont RJ, Handfield M. Distinctive characteristics of transcriptional profiles from two epithelial cell lines upon interaction with Actinobacillus actinomycetemcomitans. ACTA ACUST UNITED AC 2006; 21:261-7. [PMID: 16842512 DOI: 10.1111/j.1399-302x.2006.00281.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Transcriptional profiling and gene ontology analyses were performed to investigate the unique responses of two different epithelial cell lines to an Actinobacillus actinomycetemcomitans challenge. A total of 2867 genes were differentially regulated among all experimental conditions. The analysis of these 2867 genes revealed that the predominant specific response to infection in HeLa cells was associated with the regulation of enzyme activity, RNA metabolism, nucleoside and nucleic acid transport and protein modification. The predominant specific response in immortalized human gingival keratinocytes (IHGK) was associated with the regulation of angiogenesis, chemotaxis, transmembrane receptor protein tyrosine kinase signaling, cell differentiation, apoptosis and response to stress. Of particular interest, stress response genes were significantly - yet differently - affected in both cell lines. In HeLa cells, only three regulated genes impacted the response to stress, and the response to unfolded protein was the only term that passed the ontology filters. This strikingly contrasted with the profiles obtained for IHGK, in which 61 regulated genes impacted the response to stress and constituted an extensive network of cell responses to A. actinomycetemcomitans interaction (response to pathogens, oxidative stress, unfolded proteins, DNA damage, starvation and wounding). Hence, while extensive similarities were found in the transcriptional profiles of these two epithelial cell lines, significant differences were highlighted. These differences were predominantly found in pathways that are associated with host-pathogen interactions.
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Affiliation(s)
- J J Mans
- Center for Molecular Microbiology, Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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Andrian E, Grenier D, Rouabhia M. Porphyromonas gingivalis-epithelial cell interactions in periodontitis. J Dent Res 2006; 85:392-403. [PMID: 16632751 DOI: 10.1177/154405910608500502] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Emerging data on the consequences of the interactions between invasive oral bacteria and host cells have provided new insights into the pathogenesis of periodontal disease. Indeed, modulation of the mucosal epithelial barrier by pathogenic bacteria appears to be a critical step in the initiation and progression of periodontal disease. Periodontopathogens such as Porphyromonas gingivalis have developed different strategies to perturb the structural and functional integrity of the gingival epithelium. P. gingivalis adheres to, invades, and replicates within human epithelial cells. Adhesion of P. gingivalis to host cells is multimodal and involves the interaction of bacterial cell-surface adhesins with receptors expressed on the surfaces of epithelial cells. Internalization of P. gingivalis within host cells is rapid and requires both bacterial contact-dependent components and host-induced signaling pathways. P. gingivalis also subverts host responses to bacterial challenges by inactivating immune cells and molecules and by activating host processes leading to tissue destruction. The adaptive ability of these pathogens that allows them to survive within host cells and degrade periodontal tissue constituents may contribute to the initiation and progression of periodontitis. In this paper, we review current knowledge on the molecular cross-talk between P. gingivalis and gingival epithelial cells in the development of periodontitis.
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Affiliation(s)
- E Andrian
- Groupe de Recherche en Ecologie Buccale, Faculté de médecine dentaire, Université Laval, Quebec City, Canada
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Elkaim R, Obrecht-Pflumio S, Tenenbaum H. Paxillin phosphorylation and integrin expression in osteoblasts infected by Porphyromonas gingivalis. Arch Oral Biol 2006; 51:761-8. [PMID: 16620778 DOI: 10.1016/j.archoralbio.2006.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 02/27/2006] [Accepted: 03/01/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE We investigated early biological events initiated by Porphyromonas gingivalis infection of human osteoblasts, focusing on tyrosine-phosphorylation and the expression of key components in focal adhesion and cell signalling. DESIGN Human primary osteoblasts were challenged for 1h with Porphyromonas gingivalis. Tyrosine-phosphorylation of paxillin and focal adhesion kinase (FAK) was examined by Western blotting. Changes in alpha3- and beta1-integrin mRNA expression were quantified by RT-PCR. RESULTS Tyrosine-phosphorylation of paxillin was proportional to the size of the Porphyromonas gingivalis inoculum. FAK, a potential kinase for paxillin, was not activated. The amount of alpha3- and beta1-integrins, determined by Western blotting, did not vary significantly, while the corresponding mRNA levels fell significantly when a large bacterial inoculum was used. CONCLUSIONS These results indicate that Porphyromonas gingivalis infection of osteoblasts in vitro triggers tyrosine-phosphorylation of paxillin but not FAK and modify alpha3- and beta1-integrin mRNA expression. This infection thus appears to have different effects on components with essential roles in focal adhesion (paxillin) and cell signalling (FAK and integrins).
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Affiliation(s)
- René Elkaim
- Parogène, 11 rue Humann, 67085 Strasbourg Cedex, France
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Rodrigues PH, Progulske-Fox A. Gene expression profile analysis of Porphyromonas gingivalis during invasion of human coronary artery endothelial cells. Infect Immun 2005; 73:6169-73. [PMID: 16113342 PMCID: PMC1231123 DOI: 10.1128/iai.73.9.6169-6173.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microarrays were used to identify genes of Porphyromonas gingivalis W83 differentially expressed during invasion of primary human coronary artery endothelial cells. Analyses of microarray images indicated that 62 genes were differentially regulated. Of these, 11 genes were up-regulated and 51 were down-regulated. The differential expression of 16 selected genes was confirmed by real-time PCR.
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Affiliation(s)
- Paulo H Rodrigues
- Department of Oral Biology, University of Florida, P.O. Box 100424, Gainesville, FL 32610-0424, USA
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Madianos PN, Bobetsis YA, Kinane DF. Generation of inflammatory stimuli: how bacteria set up inflammatory responses in the gingiva. J Clin Periodontol 2005; 32 Suppl 6:57-71. [PMID: 16128830 DOI: 10.1111/j.1600-051x.2005.00821.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVES The primary aetiologic factor of periodontal disease is the bacterial biofilm. Gram-positive and gram-negative bacteria possess a plethora of structural or secreted components that may cause direct destruction to periodontal tissues or stimulate host cells to activate a wide range of inflammatory responses. These responses are intended to eliminate the microbial challenge, but may often cause further tissue damage. METHODS This review has been divided into three parts: (a) bacterial virulence factors, which includes basic information on bacterial virulence factors, and the principle inflammatory responses that host cells elicit against these factors, (b) main receptors and signalling pathways, which includes basic information about the main receptors that interact with the bacterial virulence factors, the nature of these interactions, and the activated signalling pathways that lead to inflammatory responses, and (c) initiation of inflammation, which includes a model by which the virulence factors may interact with host cells and lead to inflammatory responses in the gingiva. FINDINGS AND CONCLUSIONS Bacterial components/virulence factors may be involved in modulating inflammatory responses and include: lipopolysaccharides (LPS), peptidoglycans, lipotechoic acids, fimbriae, proteases, heat-shock proteins, formyl-methionyl peptides, and toxins. Potential host cell receptors involved in recognizing bacterial components and initiating signalling pathways that lead to inflammatory responses include: Toll-like receptors (TLRs), CD14, nucleotide-binding oligomerization domain proteins (Nod) and G-protein-coupled receptors, including formyl-methionyl peptide receptors and protease-activated receptors. Of the above bacterial and host molecules, evidence from experimental animal studies implicate LPS, fimbriae, proteases, TLRs, and CD14 in periodontal tissue or alveolar bone destruction. However, evidence verifying the involvement of any of the above molecules in periodontal tissue destruction in humans does not exist.
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Affiliation(s)
- P N Madianos
- Department of Periodontology, School of Dentistry, University of Athens, Athens, Greece.
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Walter C, Zahlten J, Schmeck B, Schaudinn C, Hippenstiel S, Frisch E, Hocke AC, Pischon N, Kuramitsu HK, Bernimoulin JP, Suttorp N, Krüll M. Porphyromonas gingivalis strain-dependent activation of human endothelial cells. Infect Immun 2004; 72:5910-8. [PMID: 15385493 PMCID: PMC517532 DOI: 10.1128/iai.72.10.5910-5918.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis is an important bacterium involved in periodontal diseases. Colonization by periodontopathogens has been associated with severe local inflammatory reactions in the connective tissue. In this study we characterized P. gingivalis-mediated infection and activation of human umbilical vein endothelial cells by using two strains of different virulence capacities, strains ATCC 53977 and DSMZ 20709. Both strains were able to adhere to and infect endothelial cells with an infection rate of 0.48% for ATCC 53977 and 0.007% for DSMZ 20709. The triggering of two signal transduction pathways in P. gingivalis-infected endothelial cells was demonstrated for both strains, with a rapid increase of p38 mitogen-activated protein kinase phosphorylation and a more delayed degradation of IkappaBalpha, followed by nuclear translocation of NF-kappaB. In addition, both strains induced enhanced expression of endothelial adhesion molecules E-selectin and intracellular adhesion molecule 1 (ICAM-1). Target cell activation was independent of bacterial fimbriae expression since the fimA knockout strain A7436 DeltafimA induced the same level of ICAM-1 as the corresponding wild type (A7436-WT). Thus, two P. gingivalis strains, ATCC 53799 and DSMZ 20709, infect endothelial cells and trigger signaling cascades leading to endothelial activation, which in turn may result in or promote severe local and systemic inflammation.
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Affiliation(s)
- Clemens Walter
- Department of Infectious Diseases, Charité, Berlin, Germany
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Affiliation(s)
- Paul J Ezzo
- Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M University System Health Science Center Dallas, Texas, USA
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Beikler T, Ehmke B, Wittstock M, Schmidt H, Karch H, Flemmig TF. Serum antibody reactivity against recombinant PrtC of Porphyromonas gingivalis following periodontal therapy. J Periodontal Res 2003; 38:276-81. [PMID: 12753365 DOI: 10.1034/j.1600-0765.2003.01405.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES In 34 patients with chronic periodontitis, the presence of IgA, IgG, and IgG subclass serum antibodies against recombinant PrtC (rPrtC) of Porphyromonas gingivalis was assessed by immunoblot analysis 24 months after therapy. METHODS rPrtC was produced from P. gingivalis ATTC 33277 using the plasmid pGEX-2T. In addition, intraoral colonization with P. gingivalis was detected by PCR in subgingival plaque and swab samples from buccal mucosae, tonsils and tongue at baseline, 10 d, and 3, 6, 9, 12, 18, and 24 months. RESULTS All patients were found to harbor P. gingivalis in the oral cavity at least once during the observation period. The identified antibody responses against the rPrtC of P. gingivalis were IgA (97%, i.e. 33/34 patients) and IgG (100%, i.e. 34/34), with an IgG subclass distribution of IgG2 (65%, i.e. 22/34 patients) > IgG3 (47%, i.e. 16/34) > IgG1 (38%, i.e. 13/34) > IgG4 (29%, i.e. 10/34). Anti-rPrtC IgA and IgG antibody reactivity was found in all but one patients (anti-rPrtC IgA negative), who tested negative for P. gingivalis at all of the assessed intraoral sites for at least 6 months before sera collection. There was no association between IgG subclass reactivity against the rPrtC of P. gingivalis and progression of periodontal attachment loss. CONCLUSION The results indicated that anti-rPrtC IgA and IgG antibodies may serve as an indicator for past or present intraoral colonization with P. gingivalis.
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Affiliation(s)
- T Beikler
- Department of Periodontology, Westfalian Wilhelms University, Münster, Germany.
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Dierickx K, Pauwels M, Van Eldere J, Cassiman JJ, Van Steenberghe D, Quirynen M. Viability of cultured periodontal pocket epithelium cells and Porphyromonas gingivalis association. J Clin Periodontol 2002; 29:987-96. [PMID: 12472991 DOI: 10.1034/j.1600-051x.2002.291103.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Porphyromonas gingivalis, one of the key pathogens in the development of periodontitis, produces a number of virulence factors that might explain its pathogenicity. One of them is the ability to adhere and invade pocket epithelium. The aim of this study was to follow, over time, the association of P. gingivalis and consequent morphological changes of the pocket epithelium cells. MATERIAL AND METHODS The association capacity of four P. gingivalis serotypes [K1, K2, K4, K- (nonencapsulated)] with in vitro cultured mono-layers from periodontal pocket epithelial cells of patients with periodontitis, was followed by fluorescence microscopy and bacterial culture. The contact time between bacteria and epithelium cells ranged from 45 min to 8 h. The microscopic evaluation allowed differentiation between dead and living cells (bacteria as well as epithelium) and description of the morphological changes after association. RESULTS A highly significant difference in the number of associating bacteria was found between dead and living epithelium cells, and between non-capsulated and capsulated strains. A significant increase in the proportion of dead pocket epithelium cells was found with prolonged association time. The morphological changes (rounding of the epithelial cell, detachment from the glass cover-slip and loss of intercellular contact) occurred faster for mono-layers inoculated with the non-encapsulated P. gingivalis strain. CONCLUSIONS This study indicates that dead pocket epithelium cells harbor more P. gingivalis cells, and that a positive correlation exists between contact time and cell death. For the P. ginigvalis species, non-encapsulated strains associate in higher number. As a result, the damage they cause to the host cell seems to occur faster than occurs in encapsulated strains. As such, cell death can be seen as the end-result of bacterial association.
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Affiliation(s)
- K Dierickx
- Catholic University of Leuven, Faculty of Medicine, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Department of Periodontology, Kapucijnenvoer 7, B-3000 Leuven, Belgium
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Srisatjaluk R, Kotwal GJ, Hunt LA, Justus DE. Modulation of gamma interferon-induced major histocompatibility complex class II gene expression by Porphyromonas gingivalis membrane vesicles. Infect Immun 2002; 70:1185-92. [PMID: 11854199 PMCID: PMC127778 DOI: 10.1128/iai.70.3.1185-1192.2002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2001] [Revised: 10/09/2001] [Accepted: 11/19/2001] [Indexed: 11/20/2022] Open
Abstract
Gamma interferon (IFN-gamma)-induced endothelial cells actively participate in initiating immune responses by interacting with CD4(+) T cells via class II major histocompatibility complex (MHC) surface glycoproteins. Previously, Porphyromonas gingivalis membrane vesicles were shown to selectively inhibit IFN-gamma-induced surface expression of HLA-DR molecules by human umbilical cord vascular endothelial cells. In this study, we demonstrated an absence of HLA-DR alpha mRNA from IFN-gamma-induced cells in the presence of P. gingivalis membrane vesicles by using reverse transcriptase-PCR and Southern blotting. Vesicles also prevented transcription of the gene encoding class II transactivator, a transactivator protein required for IFN-gamma-induced expression of MHC class II genes. In addition, the effects of vesicles on IFN-gamma signal transduction involving Jak and Stat proteins were characterized by using immunoprecipitation and Western blot analyses. Jak1 and Jak2 proteins could not be detected in endothelial cells treated with membrane vesicles. Consequently, IFN-gamma-induced phosphorylation of Jak1, Jak2, and Stat1 alpha proteins was prevented. The class II-inhibitory effect of the membrane vesicles could be eliminated by heating vesicles at 100 degrees C for 30 min or by treating them with a cysteine proteinase inhibitor. This indicates that the cysteine proteinases were most likely responsible for the absence of Jak proteins observed in vesicle-treated cells. The observed increased binding of radiolabeled IFN-gamma to vesicle-treated cells suggests that vesicles may also modulate the IFN-gamma interactions with the cell surface. However, no evidence was obtained demonstrating that vesicles affected the expression of IFN-gamma receptors. Thus, P. gingivalis membrane vesicles apparently inhibited IFN-gamma-induced MHC class II by disrupting the IFN-gamma signaling transduction pathway. Vesicle-inhibited class II expression also occurred in other IFN-gamma-inducible cells. This suggested that the ability of P. gingivalis membrane vesicles to modulate antigen presentation by key cells may be an important mechanism used by this particular bacterium to escape immunosurveillance, thereby favoring its colonization and invasion of host tissues.
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Affiliation(s)
- Ratchapin Srisatjaluk
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky 40292, USA
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Myint M, Steinsvoll S, Yuan ZN, Johne B, Helgeland K, Schenck K. Highly increased numbers of leukocytes in inflamed gingiva from patients with HIV infection. AIDS 2002; 16:235-43. [PMID: 11807308 DOI: 10.1097/00002030-200201250-00013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND HIV infection increases susceptibility for marginal periodontitis, with horizontal and rapid loss of periodontal soft tissues and alveolar bone. OBJECTIVES To examine whether numbers, distribution and some properties of mast cells, neutrophils and macrophages are normal in chronically inflamed gingiva of HIV-positive patients. METHODS Gingival biopsies were stained for mast cell tryptase and chymase, neutrophil elastase, CD68, human transforming growth factor beta(1), HLA-DR, Fc gamma RI, Fc gamma RII and Fc gamma RIII and calprotectin. RESULTS Patients at all stages of HIV infection showed radically increased numbers of mast cells and neutrophils throughout the connective tissue, and of macrophages below the oral gingival epithelium (P < 0.05). CONCLUSION HIV infection is associated with increased numbers of mast cells, macrophages and neutrophils in the chronic periodontal lesion. This may predispose for tissue destruction through the release of inflammatory mediators and effector molecules. The unusually heavy cell infiltrate throughout the gingival connective tissue may contribute to the diverging pattern of periodontal tissue loss in HIV-positive patients.
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Affiliation(s)
- Maung Myint
- Departments of Oral Biology, University of Oslo, Norway
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Houalet-Jeanne S, Pellen-Mussi P, Tricot-Doleux S, Apiou J, Bonnaure-Mallet M. Assessment of internalization and viability of Porphyromonas gingivalis in KB epithelial cells by confocal microscopy. Infect Immun 2001; 69:7146-51. [PMID: 11598091 PMCID: PMC100107 DOI: 10.1128/iai.69.11.7146-7151.2001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis (P. gingivalis) is considered to be one of the main periodontal pathogens. The goal of this work was to confirm the ability of P. gingivalis to invade host cells. We detected P. gingivalis inside KB cells by confocal microscopy and analyzed the various aspects of the adherence and internalization process. Lysates of P. gingivalis-infected KB cells were also examined using anaerobic growth techniques. The results showed the viability and ability to replicate, inside the host cells, of the internalized pathogen. The production of vesicles was also tracked for the first time. Confocal microscopy revealed P. gingivalis in a perinuclear position.
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21
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Watanabe K, Yilmaz O, Nakhjiri SF, Belton CM, Lamont RJ. Association of mitogen-activated protein kinase pathways with gingival epithelial cell responses to Porphyromonas gingivalis infection. Infect Immun 2001; 69:6731-7. [PMID: 11598045 PMCID: PMC100050 DOI: 10.1128/iai.69.11.6731-6737.2001] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2001] [Accepted: 08/03/2001] [Indexed: 12/22/2022] Open
Abstract
Mitogen-activated protein (MAP) kinase pathways are key factors in host signaling events and can also play important roles in the internalization of pathogenic bacteria by host cells. Porphyromonas gingivalis, a periodontal pathogen, can efficiently invade human gingival epithelial cells (GECs). In this study, we examined the activation of MAP kinase pathways in GECs infected with P. gingivalis. c-Jun N-terminal kinase (JNK) was activated after 5 min of infection with P. gingivalis, whereas noninvasive Streptococcus gordonii did not have a significant effect on JNK activation. In contrast, extracellular signal-regulated kinase (ERK) 1/2 was downregulated in a dose-dependent manner by P. gingivalis, but not by S. gordonii, after a 15-min exposure. Nonmetabolically active P. gingivalis cells were unable to modulate MAP kinase activity. U0126, a specific inhibitor of MEK1/2 (ERK1/2 kinase), and toxin B, a specific inhibitor of Rho family GTPases, had no effect on P. gingivalis invasion. Genistein, a tyrosine protein kinase inhibitor, blocked uptake of P. gingivalis. The transcriptional regulator NF-kappaB was not activated by P. gingivalis. These results suggest that P. gingivalis can selectively target components of the MAP kinase pathways. ERK1/2, while not involved in P. gingivalis invasion of GECs, may be downregulated by internalized P. gingivalis. Activation of JNK is associated with the invasive process of P. gingivalis.
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Affiliation(s)
- K Watanabe
- Department of Oral Biology, University of Washington, Seattle, Washington 98195, USA
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22
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Dorn BR, Dunn WA, Progulske-Fox A. Porphyromonas gingivalis traffics to autophagosomes in human coronary artery endothelial cells. Infect Immun 2001; 69:5698-708. [PMID: 11500446 PMCID: PMC98686 DOI: 10.1128/iai.69.9.5698-5708.2001] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis is a periodontal pathogen that also localizes to atherosclerotic plaques. Our previous studies demonstrated that P. gingivalis is capable of invading endothelial cells and that intracellular bacteria are contained in vacuoles that resemble autophagosomes. In this study, we have examined the trafficking of P. gingivalis 381 to the autophagic pathway. P. gingivalis 381 internalized by human coronary artery endothelial (HCAE) cells is located within vacuoles morphologically identical to autophagosomes. The progression of P. gingivalis 381 through intracellular vacuoles was analyzed by immunofluorescence microscopy. Vacuoles containing P. gingivalis colocalize with Rab5 and HsGsa7p early after internalization. At later times, P. gingivalis colocalizes with BiP and then progresses to a vacuole that contains BiP and lysosomal glycoprotein 120. Late endosomal markers and the lysosomal cathepsin L do not colocalize with P. gingivalis 381. The intracellular survival of P. gingivalis 381 decreases over 8 h in HCAE cells pretreated with the autophagy inhibitors 3-methyladenine and wortmannin. In addition, the vacuole containing P. gingivalis 381 lacks BiP but contains cathepsin L in the presence of wortmannin. These results suggest that P. gingivalis 381 evades the endocytic pathway to lysosomes and instead traffics to the autophagosome.
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Affiliation(s)
- B R Dorn
- Center for Molecular Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
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23
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Rudney JD, Chen R, Sedgewick GJ. Intracellular Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in buccal epithelial cells collected from human subjects. Infect Immun 2001; 69:2700-7. [PMID: 11254637 PMCID: PMC98209 DOI: 10.1128/iai.69.4.2700-2707.2001] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mouth may provide an accessible model for studying bacterial interactions with human cells in vivo. Using fluorescent in situ hybridization and laser scanning confocal microscopy, we found that human buccal epithelial cells from 23 of 24 subjects were infected with intracellular bacteria, including the periodontal pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, as well as other species which have yet to be identified. Buccal cell invasion may allow fastidious anaerobes to establish themselves in aerobic sites that otherwise present an unfavorable environment. Exfoliated buccal epithelial cells might provide a protected route for bacterial transmission between different oral sites within and between hosts.
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Affiliation(s)
- J D Rudney
- Department of Oral Science and Minnesota Oral Health Clinical Research Center, School of Dentistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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24
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Huang GT, Kim D, Lee JK, Kuramitsu HK, Haake SK. Interleukin-8 and intercellular adhesion molecule 1 regulation in oral epithelial cells by selected periodontal bacteria: multiple effects of Porphyromonas gingivalis via antagonistic mechanisms. Infect Immun 2001; 69:1364-72. [PMID: 11179300 PMCID: PMC98029 DOI: 10.1128/iai.69.3.1364-1372.2001] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Interaction of bacteria with mucosal surfaces can modulate the production of proinflammatory cytokines and adhesion molecules produced by epithelial cells. Previously, we showed that expression of interleukin-8 (IL-8) and intercellular adhesion molecule 1 (ICAM-1) by gingival epithelial cells increases following interaction with several putative periodontal pathogens. In contrast, expression of IL-8 and ICAM-1 is reduced after Porphyromonas gingivalis ATCC 33277 challenge. In the present study, we investigated the mechanisms that govern the regulation of these two molecules in bacterially infected gingival epithelial cells. Experimental approaches included bacterial stimulation of gingival epithelial cells by either a brief challenge (1.5 to 2 h) or a continuous coculture throughout the incubation period. The kinetics of IL-8 and ICAM-1 expression following brief challenge were such that (i) secretion of IL-8 by gingival epithelial cells reached its peak 2 h following Fusobacterium nucleatum infection whereas it rapidly decreased within 2 h after P. gingivalis infection and remained decreased up to 30 h and (ii) IL-8 and ICAM-1 mRNA levels were up-regulated rapidly 2 to 4 h postinfection and then decreased to basal levels 8 to 20 h after infection with either Actinobacillus actinomycetemcomitans, F. nucleatum, or P. gingivalis. Attenuation of IL-8 secretion was facilitated by adherent P. gingivalis strains. The IL-8 secreted from epithelial cells after F. nucleatum stimulation could be down-regulated by subsequent infection with P. gingivalis or its culture supernatant. Although these results suggested that IL-8 attenuation at the protein level might be associated with P. gingivalis proteases, the Arg- and Lys-gingipain proteases did not appear to be solely responsible for IL-8 attenuation. In addition, while P. gingivalis up-regulated IL-8 mRNA expression, this effect was overridden when the bacteria were continuously cocultured with the epithelial cells. The IL-8 mRNA levels in epithelial cells following sequential challenge with P. gingivalis and F. nucleatum and vice versa were approximately identical and were lower than those following F. nucleatum challenge alone and higher than control levels or those following P. gingivalis challenge alone. Thus, together with the protease effect, P. gingivalis possesses a powerful strategy to ensure the down-regulation of IL-8 and ICAM-1.
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Affiliation(s)
- G T Huang
- Section of Endodontics, Division of Oral Biology and Medicine and Orofacial Pain, UCLA School of Dentistry, Los Angeles, California 90095-1668, USA.
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25
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Sandros J, Karlsson C, Lappin DF, Madianos PN, Kinane DF, Papapanou PN. Cytokine responses of oral epithelial cells to Porphyromonas gingivalis infection. J Dent Res 2000; 79:1808-14. [PMID: 11077999 DOI: 10.1177/00220345000790101301] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Accumulating evidence indicates that epithelia are not merely mechanical barriers but also important elements of the innate immune system. The present study was performed to examine cytokine responses of oral epithelial cells after infection with the periodontal pathogen Porphyromonas gingivalis. The KB-cell line and primary cultures of periodontal pocket epithelium were infected with P. gingivalis for assessment of bacterial invasion by an antibiotic protection assay, and examination of expression of interleukin-1 beta, interleukin-6, interleukin-8, and tumor necrosis factor-alpha by in situ hybridization and immunohistochemistry. We observed that P. gingivalis induces a strong cytokine response, positively correlated with the adhesive/invasive potential of the infecting strain, in both KB cells and primary cultures. These findings indicate that the epithelial cells of the periodontal pocket are an integral part of the immune system, eliciting cytokine responses to a bacterial challenge. In this context, the adhesive/invasive phenotype of P. gingivalis appears to contribute to pathogenicity.
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Affiliation(s)
- J Sandros
- Department of Oral Pathology, Faculty of Odontology, Göteborg University, Sweden.
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26
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Belton CM, Izutsu KT, Goodwin PC, Park Y, Lamont RJ. Fluorescence image analysis of the association between Porphyromonas gingivalis and gingival epithelial cells. Cell Microbiol 1999; 1:215-23. [PMID: 11207554 DOI: 10.1046/j.1462-5822.1999.00022.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have developed a fluorescence imaging technique using a DNA-binding dye to visualize, over time, the physical interactions between Porphyromonas gingivalis and human gingival epithelial cells in vitro. The results extend previous observations of P. gingivalis invasion of gingival epithelial cells based on indirect measurements. An intracellular location for P. gingivalis was established by optical sectioning of images in the z-plane. Kinetic analysis showed that P. gingivalis invasion of epithelial cells is a rapid and efficient process, reaching completion after 12 min. Imaging of infected monolayers revealed that over 90% of a population of gingival epithelial cells contained bacteria. Furthermore, only vital bacteria were capable of invasion, and intracellular bacteria congregated in the perinuclear region of the epithelial cells. P. gingivalis remained inside the epithelial cells over a 24 h period and induced rearrangement of the actin cytoskeleton along with alteration of the size and shape of the epithelial cells. These findings provide direct evidence that entry rates of P. gingivalis into gingival epithelial cells are high and rapid, and that internalized bacteria initially localize in a specific region of the epithelial cells.
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Affiliation(s)
- C M Belton
- Department of Oral Biology, University of Washington, Seattle 98195, USA
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27
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Abstract
Some periodontal pathogens disrupt epithelial barriers and cellular adhesion to the extracellular matrix, which affects the cytoskeleton. Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans exploit the cytoskeleton during their uptake by epithelial cells. Treponema denticola perturbs actin and actin-regulating pathways in host cells. Cytoskeletal dysfunction due to pathogenic bacteria may impair physiologic remodeling and wound repair in the periodontium.
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Affiliation(s)
- R P Ellen
- University of Toronto, Faculty of Dentistry, 124 Edward Street, Toronto M5G 1G6, Canada
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28
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Affiliation(s)
- S C Holt
- Department of Microbiology, University of Texas Health Science Center at San Antonio, Graduate School of Biomedical Sciences, USA
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29
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van Winkelhoff AJ, Slots J. Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in nonoral infections. Periodontol 2000 1999; 20:122-35. [PMID: 10522225 DOI: 10.1111/j.1600-0757.1999.tb00160.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- A J van Winkelhoff
- Department of Oral Microbiology, Academic Centre for Dentistry Amsterdam, The Netherlands
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30
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Wells CL, Jechorek RP, Kinneberg KM, Debol SM, Erlandsen SL. The isoflavone genistein inhibits internalization of enteric bacteria by cultured Caco-2 and HT-29 enterocytes. J Nutr 1999; 129:634-40. [PMID: 10082767 DOI: 10.1093/jn/129.3.634] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The dietary isoflavone genistein is the focus of much research involving its role as a potential therapeutic agent in a variety of diseases, including cancer and heart disease. However, there is recent evidence that dietary genistein may also have an inhibitory effect on extraintestinal invasion of enteric bacteria. To study the effects of genistein on bacterial adherence and internalization by confluent enterocytes, Caco-2 and HT-29 enterocytes (cultivated for 15-18 d and 21-24 d, respectively) were pretreated for 1 h with 0, 30, 100, or 300 micromol/L genistein, followed by 1-h incubation with pure cultures of Listeria monocytogenes, Salmonella typhimurium, Proteus mirabilis, or Escherichia coli. Pretreatment of Caco-2 and HT-29 enterocytes with genistein inhibited bacterial internalization in a dose-dependent manner (r = 0.60-0.79). Compared to untreated enterocytes, 1-h pretreatment with 300 micromol/L genistein was generally associated with decreased bacterial internalization (P < 0. 05) without a corresponding decrease in bacterial adherence. Using Caco-2 cell cultures, decreased bacterial internalization was associated with increased integrity of enterocyte tight junctions [measured by increased transepithelial electrical resistance (TEER)], with alterations in the distribution of enterocyte perijunctional actin filaments (visualized by fluorescein-labeled phalloidin), and with abrogation of the decreased TEER associated with S. typhimurium and E. coli incubation with the enterocytes (P < 0.01). Thus, genistein was associated with inhibition of enterocyte internalization of enteric bacteria by a mechanism that might be related to the integrity of the enterocyte tight junctions, suggesting that genistein might function as a barrier-sustaining agent, inhibiting extraintestinal invasion of enteric bacteria.
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Affiliation(s)
- C L Wells
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapois, MN 55455-0385, USA
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31
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Dorn BR, Leung KL, Progulske-Fox A. Invasion of human oral epithelial cells by Prevotella intermedia. Infect Immun 1998; 66:6054-7. [PMID: 9826397 PMCID: PMC108773 DOI: 10.1128/iai.66.12.6054-6057.1998] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/1998] [Accepted: 09/09/1998] [Indexed: 11/20/2022] Open
Abstract
Invasion of oral epithelial cells by pathogenic oral bacteria may represent an important virulence factor in the progression of periodontal disease. Here we report that a clinical isolate of Prevotella intermedia, strain 17, was found to invade a human oral epithelial cell line (KB), whereas P. intermedia 27, another clinical isolate, and P. intermedia 25611, the type strain, were not found to invade the cell line. Invasion was quantified by the recovery of viable bacteria following a standard antibiotic protection assay and observed by electron microscopy. Cytochalasin D, cycloheximide, monodansylcadaverine, and low temperature (4 degreesC) inhibited the internalization of P. intermedia 17. Antibodies raised against P. intermedia type C fimbriae and against whole cells inhibited invasion, but the anti-type-C-fimbria antibody inhibited invasion to a greater extent than the anti-whole-cell antibody. This work provides evidence that at least one strain of P. intermedia can invade an oral epithelial cell line and that the type C fimbriae and a cytoskeletal rearrangement are required for this invasion.
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Affiliation(s)
- B R Dorn
- Department of Oral Biology, Periodontal Disease Research Center, College of Dentistry, University of Florida, Gainesville, Florida 32608, USA
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32
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Lamont RJ, Jenkinson HF. Life below the gum line: pathogenic mechanisms of Porphyromonas gingivalis. Microbiol Mol Biol Rev 1998; 62:1244-63. [PMID: 9841671 PMCID: PMC98945 DOI: 10.1128/mmbr.62.4.1244-1263.1998] [Citation(s) in RCA: 758] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis, a gram-negative anaerobe, is a major etiological agent in the initiation and progression of severe forms of periodontal disease. An opportunistic pathogen, P. gingivalis can also exist in commensal harmony with the host, with disease episodes ensuing from a shift in the ecological balance within the complex periodontal microenvironment. Colonization of the subgingival region is facilitated by the ability to adhere to available substrates such as adsorbed salivary molecules, matrix proteins, epithelial cells, and bacteria that are already established as a biofilm on tooth and epithelial surfaces. Binding to all of these substrates may be mediated by various regions of P. gingivalis fimbrillin, the structural subunit of the major fimbriae. P. gingivalis is an asaccharolytic organism, with a requirement for hemin (as a source of iron) and peptides for growth. At least three hemagglutinins and five proteinases are produced to satisfy these requirements. The hemagglutinin and proteinase genes contain extensive regions of highly conserved sequences, with posttranslational processing of proteinase gene products contributing to the formation of multimeric surface protein-adhesin complexes. Many of the virulence properties of P. gingivalis appear to be consequent to its adaptations to obtain hemin and peptides. Thus, hemagglutinins participate in adherence interactions with host cells, while proteinases contribute to inactivation of the effector molecules of the immune response and to tissue destruction. In addition to direct assault on the periodontal tissues, P. gingivalis can modulate eucaryotic cell signal transduction pathways, directing its uptake by gingival epithelial cells. Within this privileged site, P. gingivalis can replicate and impinge upon components of the innate host defense. Although a variety of surface molecules stimulate production of cytokines and other participants in the immune response, P. gingivalis may also undertake a stealth role whereby pivotal immune mediators are selectively inactivated. In keeping with its strict metabolic requirements, regulation of gene expression in P. gingivalis can be controlled at the transcriptional level. Finally, although periodontal disease is localized to the tissues surrounding the tooth, evidence is accumulating that infection with P. gingivalis may predispose to more serious systemic conditions such as cardiovascular disease and to delivery of preterm infants.
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Affiliation(s)
- R J Lamont
- Department of Oral Biology, University of Washington, Seattle, Washington 98195, USA.
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33
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Deshpande RG, Khan MB, Genco CA. Invasion of aortic and heart endothelial cells by Porphyromonas gingivalis. Infect Immun 1998; 66:5337-43. [PMID: 9784541 PMCID: PMC108667 DOI: 10.1128/iai.66.11.5337-5343.1998] [Citation(s) in RCA: 300] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Invasion of host cells is believed to be an important strategy utilized by a number of pathogens, which affords them protection from the host immune system. The connective tissues of the periodontium are extremely well vascularized, which allows invading microorganisms, such as the periodontal pathogen Porphyromonas gingivalis, to readily enter the bloodstream. However, the ability of P. gingivalis to actively invade endothelial cells has not been previously examined. In this study, we demonstrate that P. gingivalis can invade bovine and human endothelial cells as assessed by an antibiotic protection assay and by transmission and scanning electron microscopy. P. gingivalis A7436 was demonstrated to adhere to and to invade fetal bovine heart endothelial cells (FBHEC), bovine aortic endothelial cells (BAEC), and human umbilical vein endothelial cells (HUVEC). Invasion efficiencies of 0.1, 0.2, and 0. 3% were obtained with BAEC, HUVEC, and FBHEC, respectively. Invasion of FBHEC and BAEC by P. gingivalis A7436 assessed by electron microscopy revealed the formation of microvillus-like extensions around adherent bacteria followed by the engulfment of the pathogen within vacuoles. Invasion of BAEC by P. gingivalis A7436 was inhibited by cytochalasin D, nocodazole, staurosporine, protease inhibitors, and sodium azide, indicating that cytoskeletal rearrangements, protein phosphorylation, energy metabolism, and P. gingivalis proteases are essential for invasion. In contrast, addition of rifampin, nalidixic acid, and chloramphenicol had little effect on invasion, indicating that bacterial RNA, DNA, and de novo protein synthesis are not required for P. gingivalis invasion of endothelial cells. Likewise de novo protein synthesis by endothelial cells was not required for invasion by P. gingivalis. P. gingivalis 381 was demonstrated to adhere to and to invade BAEC (0.11 and 0.1% efficiency, respectively). However, adherence and invasion of the corresponding fimA mutant DPG3, which lacks the major fimbriae, was not detected. These results indicate that P. gingivalis can actively invade endothelial cells and that fimbriae are required for this process. P. gingivalis invasion of endothelial cells may represent another strategy utilized by this pathogen to thwart the host immune response.
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Affiliation(s)
- R G Deshpande
- Department of Microbiology and Immunology, Morehouse School of Medicine, Atlanta, Georgia 30320-1495, USA
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34
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35
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Van Dyke TE. Thwarting host immune responses in periodontal disease. Trends Microbiol 1998; 6:88-9. [PMID: 9582928 DOI: 10.1016/s0966-842x(98)01212-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- T E Van Dyke
- Dept of Periodontology and Oral Biology, Boston University School of Dental Medicine, MA 02118, USA.
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36
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Ko KS, Glogauer M, McCulloch CA, Ellen RP. Treponema denticola outer membrane inhibits calcium flux in gingival fibroblasts. Infect Immun 1998; 66:703-9. [PMID: 9453630 PMCID: PMC107960 DOI: 10.1128/iai.66.2.703-709.1998] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Treponema denticola is a cultivable oral spirochete which perturbs the cytoskeleton in cultured cells of oral origin, but intracellular signalling pathways by which it affects actin assembly are largely unknown. As the outer membrane (OM) of Treponema denticola disrupts actin-dependent processes that normally require precise control of intracellular calcium, we studied the effects of an OM extract on internal calcium release, ligand-gated and calcium release-activated calcium channels, and related mechanosensitive cation fluxes in human gingival fibroblasts (HGF). Single-cell ratio fluorimetry demonstrated that in resting cells loaded with Fura-2, baseline intracellular Ca2+ concentration ([Ca2+]i) was not affected by treatment with OM extract, but normal spontaneous [Ca2+]i oscillations were dramatically increased in frequency for 20 to 30 min followed by complete blockade. OM extract inhibited ATP-induced and thapsigargin-induced release of calcium from intracellular stores by 40 and 30%, respectively. Addition of Ca2+ to the extracellular pool following depletion of intracellular Ca2+ by thapsigargin and extracellular Ca2+ by EGTA yielded 59% less replenishment of [Ca2+]i in OM extract-treated than in control HGF. In cells loaded with collagen-coated ferric oxide beads to stimulate integrin-dependent calcium release, baseline [Ca2+]i was nearly doubled but was not significantly different in control and OM extract-treated cells. Magnetically generated tensile forces on the beads induced >300% increases of [Ca2+]i above baseline. Cells preincubated with OM extract exhibited dose-dependent and time-dependent reductions in stretch-induced [Ca2+]i transients, which were due to neither loss of beads from the cells nor cell death. The T. denticola OM inhibitory activity was eliminated by heating the OM extract to 60 degrees C and by boiling but not by phenylmethylsulfonyl fluoride treatment. Thus nonlipopolysaccharide, nonchymotrypsin, heat-sensitive protein(s) in T. denticola OM can evidently inhibit both release of calcium from internal stores and uptake of calcium through the plasma membrane, possibly by interference with calcium release-activated channels.
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Affiliation(s)
- K S Ko
- Department of Periodontics, Faculty of Dentistry, University of Toronto, Ontario, Canada
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