Chemotaxis and vascular permeability produced by human periodontopathic bacteria

Rediscovering Sig Socransky, the Genius and His Legacy

Some individuals make contributions so vital to their field of knowledge that their names become almost synonymous with that field. This is the case of Sig Socransky and the field of periodontal microbiology. Sig Socransky, or simply Sig, was born in Toronto, Canada and received his DDS degree from the University of Toronto in 1957. He studied microbiology and periodontology at Harvard, receiving a certificate in 1961. That same year he was recruited to work as a Research Associate at the Forsyth Dental Center. In 1968, he was nominated Senior Member of the Staff and Head of the Department of Periodontology. During his 50-year career at Forsyth, Sig published over 300 manuscripts, keeping an average of 7 publications per year. His work had an indelible impact in the fields of periodontology and oral microbiology. All these accomplishments pale in comparison with the impact that Sig had on a personal level. We have collected testimonials from some of his former students, closest collaborators, and friends in an attempt to give readers an insight into Sig’s personality. We hope we can offer those who knew him through his work a glimpse of how it felt to interact with this remarkable individual.

The major surface protein complex of Treponema denticola depolarizes and induces ion channels in HeLa cell membranes

The oral spirochete Treponema denticola is closely associated with periodontal diseases in humans. The 53-kDa major surface protein (Msp) located in the outer membrane of T. denticola serovar a (ATCC 35405) has both pore-forming activity and adhesin activity. We have used standard patch clamp recording methods to study the effects of a partially purified outer membrane complex containing Msp on HeLa cells. The Msp complex was free of the chymotrypsin-like proteinase also found in the outer membrane of T. denticola. Msp bound to several HeLa cell proteins, including a 65-kDa surface protein and a 96-kDa cytoplasmic protein. The Msp complex depolarized and increased the conductance of the HeLa cell membrane in a manner which was not strongly selective for Na+, K+, Ca2+, and Cl- ions. Cell-attached patches of HeLa cell membrane exposed to Msp complex exhibited short-lived channels with a slope conductance of 0.4 nS in physiologically normal saline. These studies show that Msp binds both a putative epithelial cell surface receptor and cytoplasmic proteins and that the Msp complex can form large conductance ion channels in the cytoplasmic membrane of epithelial cells. These properties may contribute to the cytopathic effects of T. denticola on host epithelial cells.

Involvement of treponemal surface-located protein and carbohydrate moieties in the attachment of Treponema denticola ATCC 33520 to cultured rat palatal epithelial cells

We studied the nature of attachment of Treponema denticola ATCC 33520 to a microscopically distinct population of rounded rat palatal epithelial cells. The motility of the freshly harvested spirochetes appeared not be a prerequisite for attachment. Treatment of T. denticola ATCC 3350 with proteinase-K, heat, glutaraldehyde, formaldehyde and periodate oxidation decreased the attachment to the rounded rat palatal epithelial cells, indicating the involvement of protein and carbohydrate moieties. Trypsin treatment had no effect on the attachment. The attachment of T. denticola ATCC 33520 was decreased after treatment with native non-immune rabbit serum, native polyclonal rabbit serum, D-mannose, N-acetyl-D-galactosamine and sialic acid. The results indicate that the attachment of T. denticola ATCC 33520 to rounded rat palatal epithelial cells is mediated by trypsin-resistant adhesin(s) of protein and carbohydrate nature, with affinity for D-mannose, N-acetyl-D-galactosamine and sialic acid.

Attachment of T. denticola strains ATCC 33520, ATCC 35405, B11 and Ny541 to a morphologically distinct population of rat palatal epithelial cells

In the present study an assay for the attachment of T. denticola to epithelial cells is described. An indirect immunohistochemical staining method, using two native polyclonal antisera, revealed dark-brown coloured spirochetes attached to rat palatal epithelial cell (RPE) monolayers. In addition, two morphologically distinct populations of RPE cells could be distinguished in the monolayers when using phase contrast microscopy. One minor population consisted of isolated rounded RPE cells that were lying on top of a confluent monolayer of flattened RPE cells. The rounded RPE cells were more receptive for the attachment of T. denticola than the flattened cells. The rounded RPE cells were evenly distributed over the monolayer, but the attachment of spirochetes to the rounded cells was greater at the edge than in the centre of the monolayers. The percentage of rounded RPE cells with attached spirochetes depended on the incubation time (optimum 6 h), temperature (optimum 37 degrees C) and pH (optimum 7.0). It is speculated that the attachment of T. denticola is a physical/chemical process of yet unknown nature and that differences in the number of microvilli and/or the amount of available receptors, between the two morphologically distinct cell types, accounts for the differences in the numbers of attached spirochetes.

Spirochaetes in oral infections

Oral spirochaetes, which are small-, medium- or large-sized, include species of the genus Treponema, many of which have not yet been cultured. They are found in root canal infections, pericoronitis, gingivitis and periodontitis, constituting up to 10% of the flora in endodontic abscesses, 30% in acute necrotizing ulcerative gingivitis, and 56% in advanced marginal periodontitis. The strong proteolytic activity of these organisms probably make them causes of infection rather than consequences. Being able to penetrate tissue, they bring their enzymes, metabolic products, and endotoxins, in direct contact with target cells. This may perturb essential functions of host cells and immunoglobulins. Enzyme activities may also help fulfil the complex growth requirements of spirochaetes in vivo. Reaction between infected periodontal tissue and monoclonal antibodies to Treponema pallidum has suggested that uncharacterized pathogen-related oral spirochaetes have surface structures and functions analogue to this well recognized pathogen. This warrants a more intensified search for the role of spirochaetes in oral infections.

Serum antibody responses in human periodontitis to cellular components of Capnocytophaga

Serum levels of IgM, IgG and IgG-antibody subclasses directed against cell envelopes, lipopolysaccharides and cytoplasmic fractions from Capnocytophaga sputigena, C. gingivalis and C. ochracea were examined in age-, race- and sex-matched periodontally healthy (n = 25) subjects and subjects with adult periodontitis (n = 25). The envelopes and cytoplasmic fractions were obtained by ballistic disintegration of the cells and ultracentrifugation. Cell envelopes were treated with DNase, RNase and lysozyme. Lipopolysaccharides were obtained by hot phenol-water extraction and treated with DNase and RNase. The relative levels of the antibodies in response to the cell fractions were measured by the streptavidinbiotin micro enzyme-linked immunosorbent assay. Both groups showed IgM and IgG antibodies to each fraction of the three Capnocytophaga species, but the frequency of positive IgG subclass responses varied. The IgG4 responses were lower than the other subclasses. There were no significant differences between the IgM antibody levels of the two groups. However, the adult periodontitis group had significantly lower IgG antibody titres to the cell envelopes and cytoplasmic fractions of C. gingivalis and C. ochracea, and lipopolysaccharide of C. gingivalis. These results were reflected in the depressed levels of IgG1 and/or IgG2 to these cellular fractions from the same bacterial species. The adult periodontitis group also showed a lower level of IgG1 to the cytoplasmic fractions of C. sputigena without any depression in the total IgG antibody level. There were no significant differences between the groups in IgG3 and IgG4 antibody levels to any of the cellular fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Tip-oriented adherence of Treponema denticola to fibronectin

The adherence of Treponema denticola to ligands on cell surfaces or in basement membranes of periodontal tissues might play an important role in its pathogenicity. A direct microscopic assay was used to examine the binding of T. denticola to fibronectin and other protein substrates adsorbed on plastic cover slips. All strains of T. denticola that were tested adhered to fibronectin but to different degrees. The strains which bound in high numbers frequently bound by their tips. Type strain ATCC 33520 bound to fibronectin in high numbers (149 +/- 11.3 bacteria per microscopic field), with 60% bound by the tips. Strain e' bound in high numbers (140 +/- 10.2) and had the highest percentage of tip binding (98%); strain e bound in lowest numbers (39 +/- 8.2) and had the lowest percentage of tip binding (15%). Laminin supported binding at a level similar to that of fibronectin, as did fibronectin fragments which contained the cell binding domain peptides, RGDS. Type IV collagen and non-RGDS peptides did not support binding. Binding to fibronectin and laminin was inhibited by the addition of antifibronectin and antilaminin antibodies. By lowering the incubation temperature from 37 to 4 degrees C, the number of cells that attached decreased by 60% and tip binding was reduced by 50%. Pretreatment of the cells with collagen did not affect binding, whereas fibronectin pretreatment enhanced binding by 50% and laminin pretreatment resulted in a decrease of 60%. T. denticola adheres by its tips to fibronectin-coated surfaces, which suggests that fibronectin-specific adhesins cluster at the tips.

Spirochaetes and granulocytes at sites involved in periodontal disease

Eighty-six men and 63 women with periodontitis participated in this investigation, at the start of which clinical indices were recorded and the pocket contents from one periodontally involved site for each patient were analysed. The numbers of spirochaetes, other motile microorganisms, non-motile filaments, rods or cocci and of granulocytes, monocytes and epithelial cells were determined. After non-surgical treatment 98 patients (P-group) were unsuccessfully and 51 (C-group) were successfully treated. At baseline the P-group had significantly higher numbers of spirochaetes (p = 0.0001) and polymorphonuclear leucocytes (p = 0.0256) than the C-group. The number of rods was statistically higher in the C-group (p = 0.0254). There was no significant difference between the groups with respect to the number of remaining teeth, plaque or calculus scores. Significantly higher values were found in the P-group for bleeding on probing (p = 0.0434), number of pockets greater than or equal to 5 mm (p = 0.0001), mean pocket depths (p = 0.0001), percentage bone loss per site (p = 0.0001) and the number of sites with greater than or equal to 20% bone loss on radiographs (p = 0.0001).

1985 Kreshover lecture. Molecular factors influencing neutrophil defects in periodontal disease

Major advances in our understanding of the role of the neutrophil in host defense against periodontal organisms have been made through studies of localized juvenile periodontitis (LJP). Several lines of evidence suggest that LJP is an infectious process closely associated with Actinobacillus (Haemophilus) actinomycetemomitans as a causative agent, although other organisms may also participate. The immunologic profile of LJP patients suggests that a cell-associated neutrophil locomotory dysfunction is a key underlying immunodeficiency resulting in increased susceptibility to periodontal infection. In addition, LJP patients often exhibit cervical lymphadenopathy and IgG-hypergammaglobulinemia, and a markedly elevated antibody response to the infecting organism, A. actinomycetemcomitans, is found in the serum and crevicular fluid of most patients. Evaluation of the locomotory properties of LJP neutrophils shows that random migration and chemokinesis are normal; however, about 70% of the LJP patients suffer from a defect in chemotaxis, with their neutrophils responding poorly to bacterial chemotactic factors, synthetic chemotactic peptides, and complement fragments (C5a). Depressed chemotaxis of LJP neutrophils is paralleled by their reduced capacity to bind the synthetic chemotactic peptide N-formylmethionylleucylphenylalanine (FMLP), as well as C5a. Furthermore, there is a reduction in the amount of glycoprotein 110, a neutrophil membrane matrix component and differentiation antigen which is associated with FMLP- and possibly also C5a-mediated chemotaxis. Reduction of C5a and of FMLP ligand binding, decreased expression of GP-110, and reduced neutrophil chemotaxis are consistent with a stem cell maturation error in LJP patients. This is further supported by studies demonstrating increased expression of CR2, the C3d/EBV receptor, on peripheral blood neutrophils of LJP patients. CR2 receptors are normally present on immature human neutrophils but are lost during the maturation process. These alterations in neutrophil surface components and their reduced chemotaxis may result from a genetically determined abnormality. Studies demonstrating the familial nature of both the neutrophil chemotactic disorder and the clinical entity represented by localized juvenile periodontitis point to a strong role for genetic determinants in the disease which affect neutrophil surface receptors.

The cellular host response in juvenile periodontitis. A review

The current knowledge on the cellular, host-response features in juvenile periodontitis (JP) has been reviewed. The chemotaxis of the polymorphonuclear leukocytes (PMNs), known to be defective in JP, is modulated by serum factors and bacteria. The interactions of the putative etiologic pathogen Actinobacillus actinomycetemcomitans (A.a.) and the enzyme lysozyme with PMNs modify the host defense. Data on the phagocytic capacity of the peripheral blood and gingival crevice PMNs in JP are still controversial. The monocytes exhibit similar alterations as PMNs in interaction with A.a., but the reports on defective monocyte chemotaxis are conflicting. Both bacterial challenge and genetic factors may regulate the lymphocyte response in JP.

Human neutrophil migration under agarose to bacteria associated with the development of gingivitis

In clinically healthy gingiva and increasingly with the development of inflammation, neutrophils are found in the gingival tissues and sulcus. This study evaluated the relative ability of bacteria associated with gingival health and developing inflammation to stimulate this increase in neutrophil accumulation. Dialyzed bacterial sonic extracts (BE) in buffer and pooled human serum (PHS) from pure cultures of Streptococcus sanguis. Actinomyces viscosus, A naeslundii, Bacteroides intermedius, Fusobacterium sp and Veillonella sp were tested for stimulation of human neutrophil migration under agarose. In addition, fractions of S sanguis culture fluids (CFs) from Sephadex G-10 chromatography were evaluated. All BE solutions were incubated for 1 hour at 37 degrees C and heat-inactivated prior to testing. All BEs in buffer attracted neutrophils, with the greatest responses seen to S sanguis and B intermedius followed by A viscosus. Migration to all BEs in PHS was greater than in buffer, suggesting that all BEs are capable of generating serum chemoattractants. A viscosus BE activated serum attractants to the greatest degree. CFs of S sanguis, A viscosus, and to a lesser degree, Fusobacterium sp, also attracted neutrophils. Evidence from [3H]FMLP competitive ligand-binding assays indicated that S sanguis CFs contained low molecular weight (less than 700) chemoattractants, which were probably formylmethionyl oligopeptide-like materials. Of the bacteria associated with health, S sanguis and A viscosus appeared at least as able to generate chemoattractants during growth or with exposure to serum as bacteria associated with gingivitis. This observation suggests that these "healthy" bacteria, which are found in greater numbers with developing inflammation, may mediate increased neutrophil transmigration in early disease.

A rationale for the management of periodontal diseases: effects of tetracycline on subgingival bacteria

Microbiologic criteria obtained with phase-contrast microscopy were used in a short-term, double-blind study to measure the effects of systemic tetracycline HCl on subgingival bacterial populations in advanced periodontal pockets refractory to local therapy (repeated scaling, root planing, and the subgingival administration of chemotherapeutic agents [H2O2, NaHCO3, NaCl, MgSO4]). Twenty-one subjects, selected for study, had at least one of the following conditions present after local therapy: spirochetes, motile rods, or crevicular leukocytes greater than or equal to 125 per phase-contrast microscopic field. Tetracycline HCl (1 gm/day for 14 days) was randomly distributed to 11 subjects and a placebo to ten subjects, so that neither the subjects nor investigators were aware of the prescription contents. Evaluations after two weeks disclosed that tetracycline HCl significantly reduced elevated levels of spirochetes, motile rods, and crevicular leukocytes to low or undetectable levels, whereas levels in the placebo subjects remained generally unchanged. The results clearly demonstrate the value of tetracycline HCl as an adjunct to periodontal therapy in reducing remaining suspected periodontopathic bacterial populations in advanced lesions after local therapy of scaling, root planing, and topically applied chemotherapy.

A rationale for management of periodontal diseases: rapid identification of microbial 'therapeutic targets' with phase-contrast microscopy

Monitoring the composition of subgingival flora can provide clinicians with a supplement to periodontal diagnosis and therapy. Conventional bacteriologic culturing may be clinically impractical, but direct microscopy may not.

Migration of leukocytes in dental pulp in response to plaque bacteria

Cell material from three different dental plaque bacteria (Actinomyces viscosus, Streptococcus mitis, Actinobacillus actinomycetemcomitans) were studied for their capacity to induce leukocyte migration in the dental pulp of monkeys. Altogether five animals were used to provide 123 teeth for the study. The bacterial test materials were prepared from lyophilized sonicates of pure cultures of respective bacteria mixed with crystalline bovine serum albumin (BSA) 1:1 by weight. Immediately prior to use in the experiment saline was added to render the test material into a paste-like consistency. Buccal Class V cavities were prepared in the monkey teeth leaving a thin remaining wall to the pulp. In these cavities, the test materials were enclosed for a period of 8 h. A set of control cavities received BSA alone. Placement of test and control materials were made before and after depleting the animals of serum complement by repeated injections of Cobra Venom Factor. Histologic examination of pulp tissue specimens showed that materials from two of the bacterial species (A. viscosus, Act. actinomycetemcomitans) consistently induced infiltrations of polymorphonuclear leukocytes in one to several cell layers underneath the test cavity. The material from S. mitis seemed less potent and in 11 of 22 teeth no pulpal reaction was recorded. Inactivation of complement with Cobra Venom Factor did not appear to affect the severity of the pulpal responses.

Determination of periodontal disease activity

The determination of disease activity has a direct impact on therapeutic measures in periodontics. Evaluations that may indicate disease activity have been reviewed under the topics of traditional evaluations, gingival crevicular fluid contents, tissue changes, circulating factors, and sulcular microbiota. The traditional methods, such as probing, radiographs, and clinical indices, were static evaluations that had limited validity in determining disease activity. When used in longitudinal tests, these methods may be used retrospectively to detect disease activity. Evaluation of the contents of gingival crevicular fluid has promise as a noninvasive method of determining tissue changes in the periodontium. To date, none of the crevicular fluid constituents has been a reliable indicator of disease activity. Tissue changes in the periodontium are important in understanding the disease processes but have had limited value as indicators of disease activity. The ability to determine disease activity through identification of substances or changes in the systemic circulation would prove quite useful to the clinician. Although some reports found lymphocyte transformation indicative of active disease, others had conflicting results. Finally, examinations of sulcular microbiota provided evidence suggesting that active periodontal disease was associated with specific groups of pathogens and with elevated counts of motile organisms. The evaluation of such pathogens and motile organisms currently shows the most promise for determining periodontal disease activity. However, long-term assessments and further clinical trials are necessary before this type of evaluation can be widely accepted. It is hoped that such studies will enable the clinician to predict the natural history of active and inactive periodontal disease.

Update on plaque and periodontal disease

The relationship between plaque and inflammatory periodontal disease is complex, and requires extensive and often abstruse research. One unfortunate consequence is that much relevant information concerning this relationship is not readily available to those most concerned with the prevention and treatment of inflammatory periodontal disease. The present review is concerned with some relevant developments in recent plaque research.

Neutrophil chemotaxis induced by anaerobic bacteria isolated from necrotic dental pulps

Anaerobic bacteria belonging to the species Bacteroides melaninogenicus, Bacteroides asaccharolyticus, Fusobacterium nucleatum, Peptostreptococcus anaerobius and Eubacterium alactolyticum, isolated from necrotic dental pulps, were tested for their capacity to induce neutrophil leukocyte chemotaxis. Generation of chemotactic factors in serum by whole bacterial cells and chemotaxis induced by bacterial extracts were studied in vitro by the Boyden technique. Subcutaneously implanted wound chambers in guinea pigs were used for testing leukocyte migration in vivo. All bacterial strains had a similar high capacity to induce neutrophil chemotaxis. The heavy accumulation of polymorhponuclear neutrophil leukocytes associated with clinical and experimental infections by B. melaninogenicus or B. asaccharolyticus cannot be ascribed to any extreme ability of these organisms to generate chemotactic factors.