Lymphocyte blastogenesis to plaque antigens in human periodontal disease. ii. The relationship to clinical parameters

A novel factor isolated from Actinobacillus actinomycetemcomitans stimulates mouse B cells and human peripheral blood mononuclear cells

A novel immunostimulating factor (ISTF) of Actinobacillus actinomycetemcomitans ATCC 29522 was isolated and characterized as inducing proliferation of mouse B cells and human peripheral blood mononuclear cells. This factor was isolated from the bacterial culture medium and purified by size exclusion chromatography, dye-ligand affinity chromatography, immunoaffinity chromatography using monoclonal antibodies, and preparative electrophoresis. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified ISTF migrated as a single band corresponding to a molecular mass of 13 kDa. ISTF was a proteinaceous material distinct from lipopolysaccharide; it directly induced the proliferation of B lymphocytes but had no effect on the proliferation of T lymphocytes, even in the presence of antigen-presenting cells. A B-lymphocyte-mitogenic activity of ISTF was also shown by flow cytometric analysis of responding cell subpopulations. Immunoblot analysis revealed that ISTF was a component of the outer membranes of bacteria, could exist as a soluble form, and was released by growing and/or lysed bacteria. These results suggest that ISTF produced by A. actinomycetemcomitans may play an important role in immunopathologic changes associated with A. actinomycetemcomitans infections.

Immunomodulatory and superantigen activities of bacteria associated with adult periodontitis

Immune dysfunctions are frequently associated with chronic inflammatory diseases. Several investigators have reported that patients with severe periodontitis show reduced or negligible levels of proliferative responses of peripheral blood and gingival lymphocytes to periodontopathic organisms. The purpose of this study was to evaluate the influences of products from Porphyromonas gingivalis (P. gingivalis) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) on lymphocytes obtained from periodontally diseased and non-diseased individuals in order to extend our understanding of the possible role of such bacterial components as immune modulators. Pooled cultures of either P. gingivalis or A. actinomycetemcomitans were disrupted using glass beads in a bead mill to prepare whole cell homogenates. These homogenates were then co-cultured with human peripheral blood mononuclear cells (PBMC) and known lymphocyte stimulators. Cultures were pulsed with tritiated thymidine, harvested, and radio label incorporation was determined. Responses to toxic shock syndrome toxin-1 (TSST-1) and pokeweed mitogen (PWM) were inhibited at high concentrations of bacterial homogenate. However, as the concentration was reduced, responses induced by PWM were restored while TSST-1 induced responses remained inhibited. Such results suggest that P. gingivalis and A. actinomycetemcomitans contain potent immunosuppressants with differential influences on lymphocyte population. These effects on B- and T-cells are independent of periodontal disease status and appear to exert their influence through non-toxic mechanisms. In addition, work currently underway presently indicates that obligate oral anaerobic bacteria such as P. gingivalis produce substances with some of the characteristics of superantigens.

Effect of initial treatment of chronic inflammatory periodontal disease on the frequency of peripheral blood T-lymphocytes specific to periodontopathic bacteria

Limit dilution analysis (LDA) was used to determine the effect of initial treatment of chronic inflammatory periodontal disease on the frequency of periodontopathic bacteria-specific T-cells in peripheral blood. Eleven marginal gingivitis (MG) and 8 adult periodontitis (AP) subjects took part in the study. The proliferative T-lymphocyte precursor (PTL-P) frequencies to Porphyromonas gingivalis and Actinomyces viscosus were determined using LDA and Poisson statistics both before and after treatment. Tetanus toxoid was used as a control antigen. Treatment resulted in a significant reduction in clinical disease parameters in both groups. The median peak PTL-P frequency for P. gingivalis was significantly higher in the AP group compared with the MG group before treatment. This was not the case after treatment nor with A. viscosus. In the MG group the median peak PTL-P frequency with both P. gingivalis and A. viscosus declined as a result of treatment. Although this decline was not statistically significant it may indicate an antigen-specific response in this group. In the AP group the median peak PTL-P frequency with P. gingivalis before treatment was 83.76 x 10(-6) (approximately 1 in 12,000) and after treatment it was 36.17 x 10(-6) (approximately 1 in 28,000). Dose-response relationships showed at each concentration of organisms/well this trend for a decline in PTL-P frequency after treatment, suggesting that any increased responsiveness to this organism in this group may be largely antigen-specific. However, there was no difference in this group in the median peak PTL-P frequency with A. viscosus before and after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum antibodies and loss of periodontal bone in patients with rheumatoid arthritis

The number of teeth, % of alveolar bone loss, serum IgG, and serum antibodies to Bacteroides gingivalis, Capnocytophaga ochracea and Eubacterium saburreum were recorded in 37 patients diagnosed with rheumatoid arthritis (RA) and in an age- and sex-matched control group of 37 individuals free from RA. The RA group had a significantly increased loss of teeth and loss of alveolar bone compared to the control group. The RA patients also had a significantly increased level of serum IgG. In the total material, 26% of the variation in loss of alveolar bone was accounted for by age, diagnosis of rheumatoid arthritis, and levels of antibodies against B. gingivalis and E. saburreum. In the RA group, 48% of this variation was accounted for by age, total serum IgG and IgG antibodies to B. gingivalis and E. saburreum.

Effects of culture supernatants of leukocytes from periodontal patients on monocyte-mediated hydroxyapatite resorption

In this study, the effects of culture supernatants on various activities of the monocyte, as a bone-resorbing cell, were compared between peripheral blood leukocyte (PBL) cultures from patients with periodontal disease and those from subjects with a clinically healthy periodontium. We have reported that normal human monocytes in vitro induce the release of calcium from synthetic hydroxyapatite particles and that the activity is enhanced by supernatants from cultures of stimulated or non-stimulated peripheral blood leukocytes.

Monocytes from both patients and healthy subjects induced the release of calcium from hydroxyapatite particles (HA) to an equal degree. This activity of monocytes from healthy subjects showed a statistically significant increase by addition of supernatants from stimulated or unstimulated cultures of peripheral blood leukocytes from periodontitis patients. This increase was greater than that seen with supernatants from cells of healthy controls. The Nitro Blue Tetrazolium reduction activity and [3H]-thymidine incorporation of monocytes were also increased by addition of the supernatants from leukocyte cultures from either patients or healthy controls, but no significant difference was noted in the increase.

These results suggest that the HA-resorbing activity of monocytes was enhanced by factors from cultured leukocytes. Furthermore, these studies showed that production of these factors by peripheral mononuclear cells from patients with periodontal disease was greater than that seen with cells from normal subjects.

Analysis of the specificity of natural human antibody reactive to Actinomyces

The specificity of a frequently-occurring precipitin response to soluble antigens from cell-walls and culture filtrates of A. viscosus ATCC 19246 was examined. After precipitation with isopropanol (50-75% v/v), antigen fractions of different charge and molecular weight were isolated by ion exchange and gel filtration. When heated in mineral acid or alkali above 0.15 M, each of the purified antigens lost precipitating activity, but now inhibited the precipitin reaction between serum and exogenous unheated antigen. The inhibitor was isolated over Biogel P30 and characterized as a peptide fragment (mol. wt about 2 kd) containing approximately 50 moles of ornithine and 6-12 moles, respectively, of aspartate, serine, threonine, glutamate, glycine, alanine and histidine per 100 moles amino acids. The inhibitor was totally destroyed by heating for 1.0 hr in 2.0 M HCl. Variability in the number of fragments and differences in the non-antigenic portions probably accounted for the complexity of the antigens. Ornithine, putrescine, N-acetyl putrescine and various sugars had little or no effect on the precipitin reaction with intact antigen at high concentrations (200 mM), whereas the fragment inhibited completely at 0.4 mM. This indicates that neither ornithine nor its side-chain amides are exclusively recognized by antibody. However, ornithine may be part of a larger sequence and/or important in forming the configuration recognized by the human antibodies.

An improved method for assessing the incorporation of labeled precursors into DNA by human mononuclear cells

The blastogenic responsiveness of activated lymphoid cells is usually assessed in vitro by measuring the incorporation of radioactive thymidine or iododeoxyuridine, a thymidine analog, into DNA. The accuracy of this method is compromised by the presence in activated and unactivated lymphocytes and in some of the substances used to activate them, of degradative enzymes which compete with DNA synthetase, the incorporation efficiency of exogenous precursor is inherently low. We have done studies aimed at improving both the efficiency and the accuracy of the assay system by selectively inhibiting the enzymes responsible for thymidylate synthesis de novo and DNA precursor degradation. Culture conditions were investigated and potential inhibitors were tested using human peripheral blood mononuclear cells activated with phytohemagglutinin. Nucleoside-degrading activity of mammalian and bacterial cells is due largely to nucleoside phosphorylases, enzymes that require orthophosphate for activity. We partly inhibited DNA precursor degradation by lowering the phosphate concentration in the culture medium and lowering the pH, thereby reducing the orthophosphate concentration. To reduce precursor degradation further, we tested several potential nucleoside phosphorylase and thymidylate synthetase inhibitors at various concentrations. Our data show that the addition of 1 mM fluorouracil and 1 mM deoxyuridine to the culture medium largely prevents degradation of radioactive thymidine and iododeoxyuridine without unduly compromising the DNA-labeling efficiency of cells activated with mitogens or bacterial homogenates. Under these conditions, label incorporation increases linearly as the number of blast cells or the labeling time increases.

Effect of factors other than pathologic status on responsiveness of peripheral blood mononuclear cells from patients with chronic periodontitis

Studies were designed to assess factors other than pathologic status of the cell donor which affect the blastogenic responsiveness in vitro of peripheral blood mononuclear cells (PBMs) from normal donors and patients with periodontitis. Cultures were established and activated using phytohemagglutinin-P (PHA) or homogenates of Actinomyces viscosus (AVIS), a gram-positive plaque microorganism, and Fusobacterium nucleatum (FUSO), a gram-negative plaque microorganism. Activation was assessed by measuring the incorporation of labeled precursor into DNA. The effects of incubation time, vessel shape, cell concentration, prostaglandin E2 and indomethacin on blastogenic responsiveness were studied. Blastogenic responsiveness became maximal after 5 to 8 days' activation with the bacterial substances, and after 3 days' activation with PHA. Radioactivity incorporated by cultures in microtest wells with flat, round and conical bottoms was 5.9, 7.8 and 10.6 X 10(3) cpm, respectively. Cultures of cells from all of the patients and normal subjects were activated by PHA, AVIS and FUSO, and cell concentration was a major determinant of the magnitude of the blastogenic response. Responsiveness of cultures from all patients and control subjects activated with AVIS and FUSO was inhibited significantly by prostaglandin E-2 (PGE2) at a concentration of 10 microM. Inhibition was generally 50% or greater. Indomethacin, an inhibitor of prostaglandin production, at a concentration of 0.5 micrograms/ml significantly enhanced responsiveness of AVIS- and FUSO-activated cultures from control donors and patients, indicating that prostaglandins are produced endogenously, and that they affect cell responsiveness. The effect of PGE2 and indomethacin on PHA-activated cultures was more variable and, where present, of a lesser magnitude than that observed for cultures activated with bacterial homogenates. In most cultures the effects were not statistically significant. Our data show that in studies of lymphocyte activation, the incubation time, culture-vessel shape, cell concentration and presence of endogenous inhibitors need to be taken into account.

Effects of endogenous and exogenous inhibitors on the incorporation of labeled precursors into DNA by human mononuclear cells

The degree of responsiveness of lymphoid cells to activation by mitogens and antigens is commonly assessed in vitro by measuring radioactive DNA precursor incorporation. Several lines of evidence indicate that artifacts affect the results and that these measurements may not be an accurate reflection of cell activation. Cultures of blastogenically activated lymphocytes contain soluble, noncytotoxic factors that inhibit the incorporation of radioactive nucleosides into DNA by dividing cells without affecting their rate of DNA synthesis. Inhibitors were found in the serum component of the medium and in the bacterial homogenates used to activate the cells, and they were produced by the activated cells. Inhibitor activity in serum has properties expected of a nucleoside such as thymidine, including a molecular weight of less than 10(3). The inhibitor activity present in some bacterial homogenates and that produced by activated cells enzymically degrade labeled DNA precursors, thereby preventing their availability for incorporation. Other bacterial preparations contain DNA precursors, which compete with labeled nucleosides for incorporation, and additional low-molecular-weight inhibitor is produced when the preparations are incubated. Preparations of various bacteria differ greatly with regard to the potency of their inhibitor activity. In some cases incorporation of label in activated cultures is reduced to background levels. Inhibition by these substances leads to erroneous conclusions regarding the proliferative activity of cultured lymphocytes, since the amount of label incorporated does not accurately indicate the true rate of DNA synthesis of the cells.

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.

Lymphocyte transformation responses in gingivitis and periodontitis. A review

Recent research in oral immunology has implied that cell-mediated immune reactions are a possible pathogenic mechanism in gingivitis and periodontitis. The basis for the most commonly used in vitro test, lymphocyte transformation, and the possible interpretation are explained. The application of this test to a study of medically healthy subjects with varying degrees of periodontal disease yielded conflicting results. Previous reports in the literature have not established a relationship between blastogenic responses of peripheral blood lymphocytes in periodontally diseased patients, and their disease status. The possibility of subclinical sensitization is discussed, although a cause-and-effect relationship has not been proven.

Alveolar bone loss in rats after immunization with Actinomyces viscosus

We investigated a possible cause-and-effect relationship between sensitization against Actinomyces viscosus Nyl and destructive periodontal disease in RIC-Sprague-Dawley rats. Germfree rats (66) were either immunized with A. viscosus Nyl (day 20) or orally infected with A. viscosus Nyl (days 38 and 39) or both. We measured alveolar bone loss in maxillary and mandibular molars, in vitro T-lymphocyte responsiveness, and serum antibody titers. In immunized and monoassociated rats bone loss in both jaws progressed rapidly between days 37 and 72, whereas the rate of further resorption decreased until day 100. In monoassociated rats, development of bone loss was much slower, and the maximum resorption measured was, at best, half of the bone loss compared with the former group. However, no amplification of bone loss by immunization was observed in a second experiment using 63 conventional rats kept in relative gnotobiosis. Antibody titers to A. viscosus Nyl in gnotobiotic monoassociated rats were higher in immunized animals, whereas no difference was found in the respective groups of the relative gnotobiotic experiment. The fact that immunization more than doubled alveolar bone loss in gnotobiotic monoassociated rats confirms the allergic nature of the disease. The lack of such an effect under conventional conditions points to suppressor mechanisms whose decrease might convert stable periodontal lesions into progressive ones.

Human gingival lymphocytes. I. Methodology for the isolation of human gingival lymphocytes

Various methodologies were examined for the isolation of inflammatory cells from diseased human gingiva. The best recovery of viable gingival lymphocytes (gMNC) was achieved by a method which combined initial collagenase digestion followed by gentle teasing with an 18-gauge needle.

Conversion of a stable T-cell lesion to a progressive B-cell lesion in the pathogenesis of chronic inflammatory periodontal disease: an hypothesis

Changes in the host's immunological response or, alternatively, changes in the oral microflora have been implicated as possible mechanisms by which a stable lesion of chronic inflammatory periodontal disease may become a progressive lesion leading to tissue destruction and tooth loss. It has recently been established that the progressive lesion in humans can be unequivocally considered as a B-cell response. Circumstantial evidence exists which suggests that the stable lesion is in fact a T-cell-mediated mechanism. An hypothesis is presented to explain the change from a stable to a progressive state in terms of a shift from a predominantly T-cell lesion to one involving large numbers of B-cells. Mechanisms of this shift in cell populations are considered together with a discussion of possible means of preventing such a shift.

The immunopathogenesis of progressive chronic inflammatory periodontal disease

Natural, humoral and cellular immune mechanisms have all been implicated in the pathogenesis of chronic inflammatory periodontal disease. However, confusion still exists as to the role played by each of these immunological mechanisms. Recently, characterization of the cell types within the progressive lesion has been established, in which four recognizable zones were described. Immediately subjacent to the epithelium lining the periodontal pocket both polymorphonuclear leukocytes (PMN's) and macrophages were seen, while cells deeper in the tissues had the morphological appearance of lymphocytes. The majority of these lymphocytes had a B-cell phenotype although a few T-cells and macrophages were found. On the advancing front of the lesion the cells had the morphological appearance of plasma cells, the majority of which contained IgG. Other cells found in this region had the morphology of plasma cells yet contained no cytoplasmic immunoglobulin, but they did contain substantial amounts of lysosomal enzymes. Similar cells have previously been described in periodontal disease; their frequent association with fibroblasts may suggest that they are important in the pathogenesis. Deposits of IgG and fibrin were found in the fibrous tissue band surrounding the lesion. These results are reviewed and, although the zones described were not anatomically distinct, by describing the lesion in this way it was possible to establish a convenient model to explain the immunopathogenesis of progressive chronic inflammatory periodontal disease. In this respect, progressive chronic inflammatory periodontal disease in man should be considered as a B-cell lesion.

Microbiota of gingivitis in man

A study on the predominant cultivable microorganisms inhabiting gingival crevices affected with a chronic gingivitis was carried out using the roll tube culture technique. Samples were obtained from nine individuals 25--42 years of age. Gram-positive rods make up 29.1% of the isolates and included mainly Actinomyces naeslundii, Actinomyces israelii, and Actinomyces viscosus. Streptococcus mitis and Streptococcus sanguis together made up 26.8% of the cultivable organisms. Peptostreptococcus averaged 3.0% of the organisms recovered. Gram-negative anaerobic rods constituted 25.0% of the total isolates with Fusobacterium nucleatum, Bacteroides melaninogenicus ss. intermedius. Bacteriodes ochraceus, other Bacteroides species, Selenomonas sputigena, and Campylobacter sputorum as the most predominant isolates. Haemophilus parainfluenzae averaged about 14% and Veillonella species 4.3% of the cultivable microflora. The data presented indicate that the subgingival microflora of a chronic gingivitis differs from those of healthy periodontium and advanced adult and juvenile periodontis. This might suggest that different infectious processes may be operative in various clinical entities of periodontal disease.