Role of peptide antigen for induction of inhibitory antibodies to Streptococcus mutans in human oral cavity

Low Salivary IgA Levels Against PAc (361-386) as a Risk Factor for Root Caries in Older Adults

OBJECTIVES

This study aimed to assess the intricate relationship between salivary IgA antibody levels to PAc (361-386) (PPA), mutans streptococci colonization, and root caries development in older adults.

MATERIALS AND METHODS

This study included 307 participants aged 76 years residing in Niigata city, Japan. Clinical oral examinations were performed at baseline in 2004 and 1 year later, during which the total number of untreated and treated root caries was assessed using the root decayed, filled tooth (DFT) index. The stimulated saliva samples were collected using the spitting method during the baseline survey. Salivary IgA antibody levels to amino acid residues 361-386 of Streptococcus mutans PAc were quantified using an enzyme-linked immunosorbent assay. Statistical analyses, including the χ2 test, Mann-Whitney U test, and logistic regressions, were performed to examine the association of increased root DFT with the independent variables.

RESULTS

Among the 307 participants (53.1% men), the mean root DFT at baseline was 3.77 ± 3.66, and 36.5% of the study sample exhibited increased root DFT after 1 year with a mean increment of 0.36 ± 0.48. Participants with increase in root DFT after 1 year had significantly higher rates of low PPA levels (≤ 25th percentile) than those without increased root DFT (p = 0.020). Low PPA levels (≤ 25th percentile) were significantly more likely to have an increased risk of root caries development compared with PPA levels > 25th percentile (adjusted OR: 1.88, 95% CI: 1.09-3.25).

CONCLUSION

Low PPA levels and root caries incidence correlated significantly, suggesting that low levels of salivary IgA antibody to PAc (361-386) may serve as a risk factor for increased root caries in older adults.

Association between HLA-DRB1* allele polymorphism and caries susceptibility in Han Chinese children and adolescents in the Xinjiang Uygur Autonomous Region

OBJECTIVE

The rate of caries and the mean number of decayed, missing, or filled teeth were reported to be significantly higher in children in the Xinjiang Uygur Autonomous Region than in children in eastern China. Little is known regarding the genetic basis of caries among residents of the Xinjiang Uygur Autonomous Region. This study investigated the association between HLA-DRB1 alleles and caries susceptibility in Han Chinese children and adolescents in the Xinjiang Uygur Autonomous Region.

METHODS

HLA-DRB1 allele frequency was assessed in DNA samples from buccal swabs of 42 patients with caries and 123 healthy control participants using a polymerase chain reaction method with sequence-specific primers. The chi-squared test or Fisher's exact test, followed by Bonferroni correction, was used to calculate differences in allele frequencies between groups.

RESULTS

Compared with the healthy controls, the allele frequency of HLA-DRB1*13 was significantly higher in patients with caries in the Xinjiang Uygur Autonomous Region (35.71% vs. 18.70%). The allele frequency of HLA-DRB1*09 was significantly lower in patients with caries than in healthy controls (4.76% vs. 25.20%).

CONCLUSIONS

HLA-DRB1*13 alleles could confer greater caries susceptibility, whereas HLA-DRB1*09 could be protective against caries pathogenesis, in Han Chinese children in the Xinjiang Uygur Autonomous Region.

The role of salivary sIgA as protection for dental caries activity in Indonesian children

Purpose

The aim of this study is to asses the relationship between the level of sIgA and dental caries experience in healthy children who are 6- to 9-years-old from Indonesia. The case-control study is conducted to determine the protective role of salivary secretory immunoglobulin A (sIgA) levels in the stimulated whole saliva of dental caries-active and caries-free children.

Methods

This research was done by stimulating the whole saliva which had been collected from 6- to 9-years-old children with the index def-t≥3 of 30 children as the caries-active children group and 30 children with def-t<3 as the low caries-active children group. Saliva samples were collected in sterile vials between 10 am-12 pm due to the circadian rhythm, which is at least one hour after last meal. 1,5 ml of collected salivary sample was centrifuged, then the supernatants was transferred to other tube and stored immediately to the laboratory at a temperature of –20 °C. The estimation of sIgA concentration was done by using ELISA. The differences in the level of sIgA between the two groups with caries were analyzed using the t-test afterward.

Results

The total salivary concentration of sIgA was statistically significantly higher in the low caries-active children group than in the caries-active children group.

Conclusion

The total salivary concentration of sIgA was statistically and significantly higher in the low caries-active children group than caries-active children Group. There is a negative correlation between sIgA level and dental caries activity of 6 to 9-years-old children.

Self-assembling anticaries mucosal vaccine containing ferritin cage nanostructure and glucan-binding region of S. mutans glucosyltransferase effectively prevents caries formation in rodents

Anticaries protein vaccines that induce a mucosal immune response are not effective. Therefore, development of effective and convenient anticaries vaccines is a priority of dental research. Here we generated self-assembling nanoparticles by linking the glucan-binding region of Streptococcus mutans glucosyltransferase (GLU) to the N-terminal domain of ferritin to determine whether these novel nanoparticles enhanced the immunogenicity of an anticaries protein vaccine against GLU in rodents. We constructed the expression plasmid pET28a-GLU-FTH and purified the proteins from bacteria using size-exclusion chromatography. BALB/c mice were used to evaluate the ability of GLU-ferritin (GLU-FTH) nanoparticles to induce GLU-specific mucosal and systemic responses. The protective efficiency of GLU-FTH nanoparticles was compared with that of GLU alone or a mixture of GLU and poly(I:C) after administering an intranasal infusion to Wistar rats. The phagocytosis and maturation of dendritic cells (DCs) exposed in vitro to the nanoparticles were assessed using flow cytometry. The GLU-FTH nanoparticle vaccine elicited significantly higher levels of GLU-specific antibodies compared with GLU or a mixture of GLU and poly(I:C). Immunization with GLU-FTH achieved lower caries scores compared with those of the other vaccines. Administration of GLU-FTH nanoparticles enhanced phagocytosis by DCs and their maturation. Thus, self-assembling GLU-FTH is a highly effective anticaries mucosal vaccine that enhanced antibody production and inhibited S. mutans infection in rodents.

Differences in immune response to Porphyromonas gingivalis

About 341 (average age of 38.0 ± 2.5 years) patients with periodontal disease were included in this study. All the patients were not treated for periodontal disease for a period of 6 months prior to this study. All the patients were not on any hormonal therapy. Antibodies to Porphyromonas gingivalis (P. gingivalis) were determined in blood serum by enzyme-linked immunosorbent assay (ELISA) method. Findings from this study suggest immune response to P. gingivalis is more effective in males than in females. Smoking and obesity tends to reduce effective immune response.

Roles of salivary components in Streptococcus mutans colonization in a new animal model using NOD/SCID.e2f1-/- mice

Streptococcus mutans plays an important role in biofilm formation on the tooth surface and is the primary causative agent of dental caries. The binding of S. mutans to the salivary pellicle is of considerable etiologic significance and is important in biofilm development. Recently, we produced NOD/SCID.e2f1(-/-) mice that show hyposalivation, lower salivary antibody, and an extended life span compared to the parent strain: NOD.e2f1(-/-). In this study we used NOD/SCID.e2f1(-/-) 4 or 6 mice to determine the roles of several salivary components in S. mutans colonization in vivo. S. mutans colonization in NOD/SCID.e2f1(-/-) mice was significantly increased when mice were pre-treated with human saliva or commercial salivary components. Interestingly, pre-treatment with secretory IgA (sIgA) at physiological concentrations promoted significant colonization of S. mutans compared with sIgA at higher concentrations, or with human saliva or other components. Our data suggest the principal effects of specific sIgA on S. mutans occur during S. mutans colonization, where the appropriate concentration of specific sIgA may serve as an anti-microbial agent, agglutinin, or an adherence receptor to surface antigens. Further, specific sIgA supported biofilm formation when the mice were supplied 1% sucrose water and a non-sucrose diet. The data suggests that there are multiple effects exerted by sIgA in S. mutans colonization, with synergistic effects evident under the condition of sIgA and limited nutrients on colonization in NOD/SCID.e2f1(-/-) mice. This is a new animal model that can be used to assess prevention methods for dental biofilm-dependent diseases such as dental caries.

Outer membrane vesicles of Porphyromonas gingivalis elicit a mucosal immune response

We previously reported that mutation of galE in Porphyromonas gingivalis has pleiotropic effects, including a truncated lipopolysaccharide (LPS) O-antigen and deglycosylation of the outer membrane protein OMP85 homolog. In the present study, further analysis of the galE mutant revealed that it produced little or no outer membrane vesicles (OMVs). Using three mouse antisera raised against whole cells of the P. gingivalis wild type strain, we performed ELISAs to examine the reactivity of these antisera with whole cells of the wild type or the galE mutant. All three antisera had significantly lower reactivity against the galE mutant compared to wild type. OMVs, but not LPS, retained the immunodominant determinant of P. gingivalis, as determined by ELISAs (with wild type LPS or OMVs as antigen) and absorption assays. In addition, we assessed the capacity of OMVs as a vaccine antigen by intranasal immunization to BALB/c mice. Synthetic double-stranded RNA polyriboinosinic polyribocytidylic acid [Poly (I∶C)], an agonist of Toll-like receptor 3 (TLR3), was used as the mucosal adjuvant. Vaccination with OMV elicited dramatically high levels of P. gingivalis-specific IgA in nasal washes and saliva, as well as serum IgG and IgA. In conclusion, the OMVs of P. gingivalis have an important role in mucosal immunogenicity as well as in antigenicity. We propose that P. gingivalis OMV is an intriguing immunogen for development of a periodontal disease vaccine.

Effects of mucosal care on oral pathogens in professional oral hygiene to the elderly

To elucidate the effects of mucosal care on colonization of mutans streptococci and infection of Candida species, we randomized 50 functionally dependent nursing home residents, mean age 76.1 (±7.8 years), 76% females, to receive oral professional care with or without mucosal care. During 12 months of follow-up, significant reduction in the numbers of mutans streptococci in saliva and dental plaque samples were observed in both treatment groups. However, there was no reduction in the numbers of mutans streptococci in tongue samples in the non-mucosal group (p=0.150). In the comparison between the treatment with and without mucosal care, the treatment with mucosal care showed a significant inhibition effects on numbers of nutans streptococci on the tongue surface at 6 months after the treatment as compared with the treatment without mucosal care (p=0.043). Mucosal care was not associated with any significant reduction in the rate of opportunistic infection with Candida species in any of the three sites. However, more subjects without mucosal care had Candida infection in dental plaque during the follow-up (p=0.046). Professional dental care with (versus without) mucosal care had no effect on mutans streptococci colonization in saliva or plaque. Lack of mucosal care seemed to be associated with higher rates opportunistic infections with Candida species.

Induction of neutralizing antibodies in mice immunized with an amino-terminal polypeptide of Streptococcus mutans P1 protein produced by a recombinant Bacillus subtilis strain

The oral pathogen Streptococcus mutans expresses a surface protein, P1, which interacts with the salivary pellicle on the tooth surface or with fluid-phase saliva, resulting in bacterial adhesion or aggregation, respectively. P1 is a target of protective immunity. Its N-terminal region has been associated with adhesion and aggregation functions and contains epitopes recognized by efficacious antibodies. In this study, we used Bacillus subtilis, a gram-positive expression host, to produce a recombinant N-terminal polypeptide of P1 (P1(39-512)) derived from the S. mutans strain UA159. Purified P1(39-512) reacted with an anti-full-length P1 antiserum as well as one raised against intact S. mutans cells, indicating preserved antigenicity. Immunization of mice with soluble and heat-denatured P1(39-512) induced antibodies that reacted specifically with native P1 on the surface of S. mutans cells. The anti-P1(39-512) antiserum was as effective at blocking saliva-mediated aggregation of S. mutans cells and better at blocking bacterial adhesion to saliva-coated plastic surfaces compared with the anti-full-length P1 antiserum. In addition, adsorption of the anti-P1 antiserum with P1(39-512) eliminated its ability to block the adhesion of S. mutans cells to abiotic surfaces. The present results indicate that P1(39-512), expressed and purified from a recombinant B. subtilis strain, maintains important immunological features of the native protein and represents an additional tool for the development of anticaries vaccines.

The role of anti-PAc (361-386) peptide SIgA antibody in professional oral hygiene of the elderly

OBJECTIVE

Measurement of salivary IgA antibody (PAc-peptide antibody, PPA) to amino acid residues 361-386 of Streptococcus mutans PAc, which possess a multiple binding motif to various HLA-DR molecules and a B-cell epitope that recognises the inhibiting antibody to S. mutans, is an indicator for the population numbers of mutans streptococci (MS) in human saliva. The purpose of this study was to clarify the role of PPA in infection control of MS after professional oral hygiene care.

MATERIALS AND METHODS

Thirty-nine dependently living institutionalised elderly subjects (75.9 +/- 7.5 years; 10 males, 29 females) participated in the study. The measurements of PPA, MS, total streptococci (TS) and lactobacilli (LB) were performed by ELISA and culture techniques from saliva, plaque and tongue samples from the elderly.

RESULTS

After treatment using professional oral care, the numbers of MS decreased significantly at 6 months in saliva and tongue samples from the group not having PPA in comparison with the primary data; whereas in the PPA-detected group, a significant decrease in MS number was shown immediately following professional care at 1-12 months in all samples. There was little difference in the numbers of LB at any of the time points. The numbers of TS decreased rapidly in PPA-not detected group in comparison with the PPA-detected group.

CONCLUSION

PPA may be more effective for controlling MS number in the oral cavity after professional treatment. The measurement of PPA may be used for preventive instruction to dental caries at the chair side in the clinical setting.

Relationships of anti-PAc (361-386) peptide salivary IgA antibody, eosinophils and basophils with periodontal status in the elderly

The amino acid residues 361-386 of Streptococcus mutans PAc includes an important region associated with the interaction between S. mutans and salivary components. We investigated the relationships between levels of the anti-PAc (361-386) peptide antibody (PPA) in saliva and periodontal status in 281 elderly subjects (mean age 77 years; 118 females, 163 males) by assessing dental calculus (CA), attachment loss (AL), pocket depth (PD), bleeding on probing (BOP) and various blood parameters. Enzyme-linked immunosorbent assay results revealed that subjects with a PPA level of greater than 0.1 (PPA detected group) showed a lower average value for number of sites with more than 6 mm of AL/6 points x 100/tooth (rAL6) than those with a PPA level of less than 0.1 (PPA not detected group). Furthermore, average values for rAL6 were significantly lower in the PPA detected group, and BOP, AL and rAL6 correlated positively and significantly with the percentage of eosinophils present in leukocytes in female subjects in both groups. PPA level had a negative correlation with percentages of basophils and eosinophils. The results indicate that systemic increases in numbers of eosinophils and basophils are associated with the development of periodontal diseases, while PPA level may be a useful indicator of periodontal status.

Relationship of cariogenic bacteria levels with periodontal status and root surface caries in elderly Japanese

OBJECTIVE

The relationship of the levels of cariogenic bacterial species with periodontal status and decayed root surfaces was investigated in elderly Japanese subjects.

METHODS

Three hundred and sixty-eight individuals (each 75 years old) were examined for periodontal status (pocket depth, attachment loss), root surface caries and salivary levels of mutans streptococci (MS) and lactobacilli (LB).

RESULTS

Values >4 mm of attachment loss (rAL4) and for average attachment loss (aAL) of sites measured were significantly higher in subjects with LB than those without. Multiple regression analysis also showed a correlation between aAL and rAL4 values with the presence of LB (aAL p = 0.003; rAL4 p = 0.002). Further, multiple regression analysis of interacting factors regarding decayed root surfaces showed that LB carriers had a greater incidence of decayed root surface caries (p = 0.003), while MS and LB levels were correlated to the number of decayed root surfaces (LB p = 0.010; MS p = 0.026).

CONCLUSION

Our results indicate that considerable attachment loss elevates the possibility of having LB, thus increasing the risk of root surface caries. It was also found that LB and MS measurements may be useful indicators of decayed root surfaces in elderly individuals with attachment loss.

Assessment of genes associated with Streptococcus mutans biofilm morphology

Streptococcus mutans, the major pathogen responsible for dental caries in humans, is a biofilm-forming bacterium. In the present study, 17 different pulsed-field gel electrophoresis patterns of genomic DNA were identified in S. mutans organisms isolated clinically from whole saliva. The S. mutans isolates showed different abilities to form biofilms on polystyrene surfaces in semidefined minimal medium cultures. Following cultivation in a flow cell system in tryptic soy broth with 0.25% sucrose and staining using a BacLight LIVE/DEAD system, two strains, designated FSC-3 and FSC-4, showed the greatest and least, respectively, levels of biofilm formation when examined with confocal laser scanning microscopy. Further, image analyses of spatial distribution and architecture were performed to quantify the merged green (live cells) and red (dead cells) light. The light intensity of the FSC-3 biofilm was greater than that of the FSC-4 biofilm in the bottom area but not in the top area. S. mutans whole-genome array results showed that approximately 3.8% of the genes were differentially expressed in the two strains, of which approximately 2.2%, including bacitracin transport ATP-binding protein gene glrA and a BLpL-like putative immunity protein gene, were activated in FSC-3. In addition, about 1.6% of the genes, including those associated with phosphotransferase system genes, were repressed. Analyses of the glrA-deficient strains and reverse transcription-PCR confirmed the role of the gene in biofilm formation. Differential assessment of biofilm-associated genes in clinical strains may provide useful information for understanding the morphological development of streptococcal biofilm, as well as for colonization of S. mutans.

Human T-cell responses to oral streptococci in human PBMC-NOD/SCID mice

We investigated cellular and humoral immune responses to oral biofilm bacteria, including Streptococcus mutans, Streptococcus anginosus, Streptococcus sobrinus, and Streptococcus sanguinis, in NOD/SCID mice immunized with human peripheral blood mononuclear cells (hu-PBMC-NOD/SCID mice) to explore the pathogenicity of each of those organisms in dental and oral inflammatory diseases. hu-PBMC-NOD/SCID mice were immunized by intraperitoneal injections with the whole cells of the streptococci once a week for 3 weeks. FACS analyses were used to determine the percentages of various hu-T cell types, as well as intracellular cytokine production of interleukin-4 and interferon-gamma. Serum IgG and IgM antibody levels in response to the streptococci were also determined by enzyme-linked immunosorbent assay. S. anginosus induced a significant amount of the proinflammatory cytokine interferon-gamma in CD4(+) and CD8(+) T cells in comparison with the other streptococci. However, there was no significant differences between the streptococci in interleukin-4 production by CD4(+) and CD8(+) T cells after inoculation. Further, S. mutans significantly induced human anti-S. mutans IgG, IgG(1), IgG(2), and IgM antibodies in comparison with the other organisms. In conclusion, S. anginosus up-regulated Th1 and Tc1 cells, and S. mutans led to increasing levels of their antibodies, which was associated with the induction of Th2 cells. These results may contribute to a better understanding of human lymphocyte interactions to biofilm bacteria, along with their impact on dental and mucosal inflammatory diseases, as well as endocarditis.