Salivary immunoglobulin A and serum antibodies to Streptococcus mutans ribosomal preparations in dental caries-free and caries-susceptible human subjects

The oral microbiome and the immunobiology of periodontal disease and caries

The composition of the oral microbiome differs from one intraoral site to another, reflecting in part the host response and immune capacity at each site. By focusing on two major oral infections, periodontal disease and caries, new principles of disease emerge. Periodontal disease affects the soft tissues and bone that support the teeth. Caries is a unique infection of the dental hard tissues. The initiation of both diseases is marked by an increase in the complexity of the microbiome. In periodontitis, pathobionts and keystone pathogens such as Porphyromonas gingivalis appear in greater proportion than in health. As a keystone pathogen, P. gingivalis impairs host immune responses and appears necessary but not sufficient to cause periodontitis. Historically, dental caries had been causally linked to Streptococcus mutans. Contemporary microbiome studies now indicate that singular pathogens are not obvious in either caries or periodontitis. Both diseases appear to result from a perturbation among relatively minor constituents in local microbial communities resulting in dysbiosis. Emergent consortia of the minor members of the respective microbiomes act synergistically to stress the ability of the host to respond and protect. In periodontal disease, host protection first occurs at the level of innate gingival epithelial immunity. Secretory IgA antibody and other salivary antimicrobial systems also act against periodontopathic and cariogenic consortia. When the gingival immune response is impaired, periodontal tissue pathology results when matrix metalloproteinases are released from neutrophils and T cells mediate alveolar bone loss. In caries, several species are acidogenic and aciduric and appear to work synergistically to promote demineralization of the enamel and dentin. Whereas technically possible, particularly for caries, vaccines are unlikely to be commercialized in the near future because of the low morbidity of caries and periodontitis.

Minor salivary glands and dental caries: Approach towards a new horizon

Introduction:

Reduction of functioning minor salivary glands may contribute to emergence of mucosal infections, mucosal ulceration, and possibly dental caries. A study was, therefore, designed to understand the exact role of minor salivary gland secretions over dental caries.

Methodology:

We studied the average labial distribution of functional minor salivary glands using various pre-defined locations, counted the minor salivary gland secretion imprints, and correlated the decayed missing filledlevels in subjects. The functional level and amount of secretion of minor salivary gland were evaluated. The radial immunodiffusion was performed by Diffu-Plate kit and the dimensions of the ring were correlated with the amount of immunoglobulin A in saliva.

Results:

The mean number of functional labial minor salivary glands, amount of secretion, level of glycoprotein secretion, and immunoglobulin A secretion levels could very well dictate the functional status and role of minor salivary glands over caries assessment.

Conclusion:

The above-mentioned tests could be of major significance in routine diagnosis of the most common oral disease, i.e., dental caries.

Case definition, aetiology and risk assessment of early childhood caries (ECC): a revisited review

AIM

To provide a review of the existing literature on early childhood caries (ECC) with particular reference on the nomenclature, case definition, epidemiology, etiology and risk assessment.

METHODS

An electronic search was used to identify and critically review papers that have been published and are pertinent to the above issues, evaluate and compile the reported evidence.

RESULTS

The term ECC has been adopted to more accurately describe dental caries that affects primary dentitions, replacing previously used terminology that associated the disease with the nursing habit. Suggested ECC case definition uses caries patterns as defining criteria, however, further refinement to include different clinical expressions of a varying severity is necessary. Significant percentages of preschool child populations are affected by ECC today, with the disease concentrating disproportionately in deprived families. Early colonization by mutans streptococci (MS) is associated with increased ECC development, with bacteria being transmitted in both vertical and horizontal ways. Dietary factors related to sugar consumption predispose to early MS colonization and establishment and increase the risk for ECC development, being part of the causal chain. Inappropriate bottle and breast-feeding behaviors also increase the risk, without showing a direct causal relationship. High risk children belong to ethnic minority groups and to low income families with poor parental behaviors and attitudes.

CONCLUSIONS

Further high-quality studies are needed to explore the role bacteria other than MS may play in caries initiation and progression, elucidate the interaction of the saliva immune defence system with a potentially defective tooth, and investigate the effect distant behavioral factors have on the causal chain that leads to ECC development.

Salivary and serum antibody response to Streptococcus mutans antigens in humans

Humoral immunity against Streptococcus mutans infection was analyzed in caries-active and caries-free young adults by immunoblotting. All volunteers from both groups had detectable salivary immunoglobulin A (IgA) and serum IgG antibodies, with similar profiles. They could be classified on the basis of relative intensity of the immunoblot bands into categories of high or low responders. Common protein antigens with molecular weight ranging from approximately 45 to 190 kDa could be found either extracellularly or associated with the cell wall of S. mutans cultured in vitro. The predominant reactive antigens recognized by both IgA and IgG were of proteins around 63 and 60 kDa. Detection of IgA antibodies to the various antigens of S. mutans in individual saliva samples did not always correlate with serum IgG antibody profiles. In addition, distinct bands, which reacted preferentially with either IgA or IgG, could be detected by antibodies from specific subjects. Differential reactivities of salivary IgA and serum IgG antibodies to two, cell-wall associated protein antigens around 33 and 36 kDa were found in caries-active and caries-free young adults; 30.8% of caries-free subjects and 12% of caries-active subjects (P < 0.01) exhibited detectable antibody response to these antigens. This difference was not attributable to variations in antibody levels, since antibody response to these proteins were still detectable in some caries-free but not caries-active individuals whose levels of antibodies to other antigens were low. Thus, a new antibody profile which correlates with dental caries disease activity has been identified in a selected population. Differences in mucosal and systemic immune responses to S. mutans seem to be both antigen and host dependent.

Biological mechanisms of early childhood caries

The present paper reviews biological issues in early childhood caries (ECC) in light of the current understanding of the field. Despite the general global decline in dental caries in the past decades, ECC has become a significant problem in many developing countries and some minority communities in western industrialized nations. Like other types of caries, ECC is caused by mutans streptococci that ferment dietary carbohydrates to produce acid attacks on susceptible teeth over a period of time. However, while the general etiology of ECC appears similar to that of other types of caries, the predisposing factors are still unclear. The biology of ECC may be modified by several factors unique to young children, related to the implantation of cariogenic bacteria, immaturity of the host defense systems, as well as behavioral patterns associated with feeding and oral hygiene in early childhood.

Longitudinal analysis of the association of human salivary antimicrobial agents with caries increment and cariogenic micro-organisms: a two-year cohort study

Previous studies of the possible associations of salivary antimicrobial agents with dental caries have given controversial results, obviously mainly because almost all studies have been cross-sectional. Our aim was to find out, in a two-year longitudinal follow-up study, the associations among selected salivary non-immune and immune antimicrobial variables, cariogenic bacteria, and caries increment. The study population was comprised of 63 subjects, all of whom had their 13th birthday during the first study year. In addition to a comprehensive dental examination at baseline and after 2 yrs, paraffin-stimulated whole saliva samples were collected in a standardized way at six-month intervals. Saliva samples were analyzed for flow rate, buffer effect, lysozyme, lactoferrin, total peroxidase activity, hypothiocyanite, thiocyanate, agglutination rate, and total and specific anti-S. mutans IgA and IgG, as well as for numbers of total and mutans streptococci, lactobacilli, and total anaerobic bacteria. Cluster analysis and Spearman-Rank correlation coefficients were used to explore possible associations between and among the studied variables. During the two-year period, a statistically significant increase was observed in flow rate, thiocyanate, agglutination rate, anti-S. mutans IgA antibodies, lactobacilli, and total anaerobes, whereas lysozyme, lactoferrin, and total and anti-S. mutans IgG antibodies declined significantly. Based on various analyses, it can be concluded that, at baseline, total IgG and hypothiocyanite had an inverse relationship with subsequent two-year caries increment, anti-S. mutans IgG antibodies increased with caries development, and mutans streptococci and lactobacilli correlated positively with both baseline caries and caries increment. Total anaerobic microflora was consistently more abundant among caries-free individuals. In spite of the above associations, we conclude that none of the single antimicrobial agents as such has sufficiently strong power to have diagnostic significance in vivo with respect to future caries.

Kinetics of specific salivary IgA responses in man after oral challenge by ribosomal immunostimulant

The kinetics of specific IgA mucosal responses was assessed in 12 healthy volunteers over 3 weeks of treatment by oral administration of an immunostimulant, Ribomunyl, composed of ribosomes from the four bacteria Streptococcus pyogenes, Streptococcus pneumoniae, Klebsiella pneumoniae and Haemophilus influenzae. The levels of IgA specific for these four bacteria increased after each immunization and, after the third week of treatment, were significantly higher than baseline day 0 values. This study demonstrates that oral ribosomal immunostimulation results in the production of specific salivary antibodies liable to recognize whole bacteria antigens, and therefore likely to confer protection. The kinetic analysis performed also demonstrates the rapidity of specific mucosal immune responses after oral stimulation in man, a feature still seldom explored.

Antigenicity of a synthetic peptide from glucosyltransferases of Streptococcus mutans in humans

Human salivary immunoglobulin A (IgA) and serum IgG antibodies to the Streptococcus mutans glucosyltransferases (Gtfs) and to a synthetic peptide of 19 amino acids from a conserved region in the Gtfs (residues 435 to 453) were determined in young adults by enzyme-linked immunosorbent assay. Varying levels of antibody to Gtfs were detected in saliva or serum, with significantly higher levels of antibody to GtfD than to GtfB/C or GtfC. Anti-Gtf IgA levels in saliva did not correlate with those of IgG in serum. Caries-free (CF) volunteers exhibited significantly higher salivary IgA antibody levels to the peptide and to GtfB/C or GtfC than did the caries-active (CA) subjects. Preincubation of CF saliva and serum with the peptide inhibited the antibodies to the Gtfs in a dose-dependent manner, whereas preincubation of the samples from the CA group resulted in only partial inhibition. Our results indicated that this 19-amino-acid peptide includes one of the major B-cell epitopes of Gtfs and that CF individuals have higher titers of antibodies than CA subjects.

Characterization of preparations enriched for Streptococcus mutans fimbriae: salivary immunoglobulin A antibodies in caries-free and caries-active subjects

The ability of bacteria to adhere to salivary pellicle-coated enamel tooth surfaces is a critical step in oral bacterial colonization. Oral bacteria adhere to receptors of host origin in salivary pellicle. Streptococcus mutans has been identified as the major etiological agent of human dental caries and composes a significant proportion of the oral streptococci in carious lesions. Bacterial fimbriae are small (100 to 300 nm) hairlike appendages emanating from the cell surface. Preparations enriched for S. mutans fimbriae were isolated by a shearing technique and alternating high- and low-speed centrifugations. A representative fimbrial preparation had two distinct double bands comprising four proteins of approximately 100 to 200 kDa and one faint band at 40 kDa on reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis/immunoblots and had demonstrable glucosyltransferase activity. Rabbit antisera raised against the preparation specifically stained the fuzzy coat of S. mutans, demonstrating short fimbria-like structures protruding 100 to 200 nm from the cell surface. Controls without antifimbria antibody did not exhibit this staining. There were significantly higher (P < or = 0.05) levels of salivary immunoglobulin A, but not serum immunoglobulin G, antibodies to the enriched S. mutans fimbria preparation by enzyme-linked immunosorbent assay from caries-free subjects than from caries-active subjects. The results suggest that S. mutans fimbriae may be an important adherence factor to which caries-free subjects mount a protective salivary immune response.

Does variability in salivary protein concentrations influence oral microbial ecology and oral health?

Salivary protein interactions with oral microbes in vitro include aggregation, adherence, cell-killing, inhibition of metabolism, and nutrition. Such interactions might be expected to influence oral ecology. However, inconsistent results have been obtained from in vivo tests of the hypothesis that quantitative variation in salivary protein concentrations will affect oral disease prevalence. Results may have been influenced by choices made during study design, including saliva source, stimulation status, control for flow rate, and assay methods. Salivary protein concentrations also may be subject to circadian variation. Values for saliva collected at the same time of day tend to remain consistent within subjects, but events such as stress, inflammation, infection, menstruation, or pregnancy may induce short-term changes. Long-term factors such as aging, systemic disease, or medication likewise may influence salivary protein concentrations. Such sources of variation may increase the sample size needed to find statistically significant differences. Clinical studies also must consider factors such as human population variation, strain and species differences in protein-microbe interactions, protein polymorphism, and synergistic or antagonistic interaction between proteins. Salivary proteins may form heterotypic complexes with unique effects, and different proteins may exert redundant effects. Patterns of protein-microbe interaction also may differ between oral sites. Future clinical studies must take those factors into account. Promising approaches might involve meta-analysis or multi-center studies, retrospective and prospective longitudinal designs, short-term measurement of salivary protein effects, and consideration of individual variation in multiple protein effects such as aggregation, adherence, and cell-killing.

Bacterial crude extracts or ribosomes are recognized similarly by peripheral and mucosal B cells

Bacterial ribosomes have been shown to induce effective humoral and cellular immunological responses to whole microorganisms. In this study, the numbers of specific antibody producing cells directed towards Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae ribosomes or whole bacteria sonicates were compared in the peripheral blood and tonsils of 7 children, and in the tonsils, mesenteric and cervical lymph nodes of 10 sheep. No significant difference was noted between the two types of antigens, confirming that ribosomal preparations are able to mimic the immunogenicity of whole bacteria in the mucosae-associated lymphoid tissue.

Nature vs. nurture in dental caries

Why are some people more resistant to dental caries than others? Certainly diet plays a part, but are there hereditary factors that affect caries development? This report explores genetic components that appear related to caries resistance and susceptibility.

Humoral IgG antibodies to oral microbiota in a population at risk for root-surface caries

Mutans streptococci have been strongly implicated in the initiation of dental caries on coronal surfaces. Their role in development of root-surface caries is less clear. The etiologic agents of both types of dental caries are likely to elicit systemic immune responses. The objective of the present study, therefore, was to study the association of clinical variables of disease with humoral IgG antibodies to nine oral micro-organisms in 314 adult subjects, aged 45-65 years, who were at risk for root-surface caries. Antibody activity to Streptococcus mutans strain Ingbritt, S. mutans/S. sobrinus GTFs, S. faecalis strain 19433, Actinomyces viscosus strain WVU 626, Actinomyces naeslundii strain 12, Lactobacillus casei, Actinobacillus actinomycetemcomitans strain Y4, Porphyromonas gingivalis strain 381, Eikenella corrodens strain 1073, and Wolinella recta strain 371 was measured by ELISA. Pearson correlation coefficients among log10 antibody levels within subjects revealed marked positive correlations among subgingival bacteria, generally weak positive correlations among supragingival micro-organisms, and no correlations between elements of the supragingival battery with the subgingival battery. IgG antibody levels to mutans streptococcal antigens were significantly correlated with subject DMF scores (r = 0.23; p less than 0.0001). No significant correlation was seen between DMF scores and antibody to any other supragingival micro-organism tested. Further relationships between levels of S. mutans antibody and individual clinical variables were analyzed by step-wise multiple linear regression, resulting in a model that was highly significant (p = 0.0001), with an r2 = 0.14. Numbers of missing teeth, coronal caries, root-surface caries, and root-surface restorations were each positively associated with antibody levels to mutans streptococci.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of smokeless tobacco use in humans on mucosal immune factors

To assess the effects of smokeless tobacco on the secretory immune system and dental caries, we examined users of smokeless tobacco and non-tobacco users. There were no significant differences in the prevalence of DMFS between users and non-users. There was significantly more salivary IgA, IgA2 and J-chain in users. Levels of salivary lysozyme and lactoferrin were significantly lower in users than controls. Because there was no difference in levels of secretory component in relation to the increased IgA levels of smokeless tobacco users, this suggests an effect of smokeless tobacco on secretory epithelial cells responsible for synthesis of secretory component, lysozyme and lactoferrin, and for the packaging of secretory component on IgA. There were only slight differences in salivary or serum antibody levels to Streptococcus mutans. These findings indicate that although smokeless tobacco has a significant influence on the synthesis of secretory IgA, the numbers of DMFS were similar between smokeless tobacco users and controls.

Characterization of immune response to oral administration of Streptococcus sobrinus ribosomal preparations in liposomes

Gnotobiotic rats gastrically intubated with a total of 12.5 micrograms of Streptococcus sobrinus ribosomal protein incorporated into cholesterol-based liposomes had significantly (P less than or equal to 0.01) fewer carious lesions on their molar surfaces than did nonimmunized infected controls after challenge with a virulent organism. The immunized animals had significantly (P less than or equal to 0.01) lower numbers of molar-adherent S. sobrinus cells and higher levels of salivary immunoglobulin A antibodies to S. sobrinus whole cells and ribosomes than did the control group. Dose-response studies indicated that 12.5 micrograms of S. sobrinus ribosomal protein in liposomes induced slightly higher immune responses than did 62.5, 125.0, and 250.0 micrograms of ribosomal protein incorporated into liposomes. Intubation of rats with up to 250.0 micrograms of S. sobrinus ribosomal protein alone was no more effective in reducing the numbers of molar-adherent S. sobrinus cells than were nonimmunized infected controls, establishing that insertion of ribosomes into liposomes was required for inducing an effective immune response. These results indicate that oral administration of as little as 12.5 micrograms of S. sobrinus ribosomal protein incorporated into liposomes can protect rats from caries formation after challenge with the virulent organism by inducing specific salivary immunoglobulin A antibodies which can inhibit colonization by the challenged S. sobrinus.