Induction of immune responses and prevention of alveolar bone loss by intranasal administration of mice with Porphyromonas gingivalis fimbriae and recombinant cholera toxin B subunit

INTRODUCTION: Adult periodontitis is initiated by specific periodontal pathogens represented by Porphyromonas gingivalis; however, an effective measure for preventing the disease has not yet been established. In this study, the effectiveness of a vaccine composed of fimbriae of P. gingivalis and recombinant cholera toxin B subunit (rCTB) was evaluated using BALB/c mice. METHODS: Fimbriae and rCTB were co-administered intranasally to BALB/c mice on days 0, 14, 21, and 28. On day 35, mice were sacrificed to determine immunoglobulin levels in serum, saliva, and nasal and lung extracts by enzyme-linked immunosorbent assay. The prevention effect of the vaccine on P. gingivalis-induced periodontitis in mice was evaluated by measuring alveolar bone loss. RESULTS: The rCTB significantly increased serum immunoglobulin (Ig)A levels when mice were administered with a minimal amount (0.5 microg) of the fimbrial antigen. The adjuvant effect on serum IgG production was indistinct because the minimal amount of the antigen still induced a large amount of IgG. In contrast to systemic responses, a fimbria-specific secretory IgA response was strongly induced by co-administration of rCTB and 0.5 microg fimbriae; the same amount of the antigen alone scarcely induced a response. Histopathological examination revealed IgA-positive plasma cells in the nasal mucosal tissue but no observable mast cells in the area. In addition, nasal administration of the fimbrial vaccine significantly protected the mice from P. gingivalis-mediated alveolar bone loss. CONCLUSION: Nasal vaccination with a combination of fimbriae and rCTB can be an effective means of preventing P. gingivalis-mediated periodontitis.     

Production and characterization of monoclonal antibodies specific for Bacteroides gingivalis

With the aim of producing specific serological reagents for a direct quantitative evaluation of clinical plaque samples, 12 hybrid cell lines secreting monoclonal antibodies specific for Bacteroides gingivalis , were raised. The specificity of the antibodies was established by enzyme-linked immunosorbent assays and by indirect immunofluorescence tests involving a panel of 65 strains from 32 species, most of which have an oral habitat. When analysed for different reactivity patterns with various B. gingivalis strains the monoclonal antibodies were found to recognize 2 principal serogroups, which may have the same respective strain composition as previously detected virulence and serogroups. All recognized antigens were found to be expressed on the surface of the bacteria. Immunoblotting tests and analyses of the sensitivity of the recognized epitopes to various denaturing treatments suggested that 3 of 4 monoclonal antibodies reactive with all B. gingivalis strains tested, were directed to lipopolysaccharide epitopes. In contrast, the epitopes with a restricted expression on strains W83 and W50 (serogroup B) appeared to consist of outer membrane carbohydrate moieties.     

Detection of, and anti-collagen antibody produced by, CD5-positive B cells in inflamed gingival tissues

This study was performed to investigate the frequency and distribution of CD5-positive (CD5+) B cells in inflamed gingival tissues using flow cytometric and immunohistochemical analyses. The ability of CD5+ B cells to produce anti-type I collagen antibody was also examined. CD5+ B cells expressed "low" fluorescence intensity in the peripheral blood of both healthy subjects and patients with adult periodontitis. However, in inflamed gingival tissues the intensity of this surface marker was high. The percentage of B cells bearing CD5 surface marker was statistically higher in gingiva than in peripheral blood obtained from both the patients and healthy subjects. These CD5+ B cells were observed in gingival subepithelial connective tissues from the bottom to the middle of the periodontal pocket. This area showed destruction of collagen fibers and dense cell infiltrations. Anti-collagen IgG antibody level in patients' gingival crevicular fluids (GCF) was higher than that in sera from healthy subjects, and slightly higher than in autologous sera. IgM anti-collagen antibody in GCF was lower than in autologous sera and in sera from healthy subjects. EBV-transformed CD5+ B cells produced considerably more IgM and IgG antibody to collagen than CD5- B cells. Therefore CD5+ B cells may contribute to the pathogenesis of inflamed gingival tissues.     

Effect of adoptive transfer of antigen-specific B cells on periodontal bone resorption

BACKGROUND AND OBJECTIVES: Host immune responses to periodontal pathogens have been considered to contribute to the alveolar bone destruction in periodontitis. However, the role of B lymphocytes in the pathogenesis of periodontal bone loss is not clear. METHODS: We examined the effect of adoptive transfer of antigen-specific B cells from rat spleens on experimental periodontal bone resorption. Donor rats were immunized intraperitoneally (i.p.) with formalin-killed Actinobacillus actinomycetemcomitans. Antigen-specific B cells were prepared from splenocytes by first binding CD43(+) cells to Petri dishes coated with anti-CD43 antibody to remove T cells, and non-binding cells were passed through a nylon wool column to deplete accessory cells. The retained cells were then collected and bound to A. actinomycetemcomitans-coated Petri dishes for enrichment of A. actinomycetemcomitans-binding B cells (AAB). A. actinomycetemcomitans non-binding B cells (ANB) and B cells from non-immunized donor rats (NIB) were also collected from these procedures. Each type of B cell was injected into a group of recipient rats that were then orally infected with live A. actinomycetemcomitans. RESULTS: At termination, the antibody levels to A. actinomycetemcomitans in serum and gingival wash fluids were significantly higher in the recipients transferred with AAB when compared to the recipients transferred with ANB or NIB. A markedly elevated number of antibody-forming cells were observed in the spleens of the recipients transferred with AAB, and these recipient rats also exhibited significantly increased bone resorption when compared to the other groups. CONCLUSIONS: It is suggested that B cells can contribute to periodontal bone resorption and that antigen-triggering of B cells is required for the bone resorption.     

Prevalence of Bacteroides forsythus, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans in subgingival microflora of Japanese patients with adult and rapidly progressive periodontitis

BACKGROUND, AIMS: This study investigated the prevalence of Bacteroides forsythus, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans among various periodontitis patients and healthy individuals in Japan, and correlated it with clinical parameters. METHOD: Subgingival plaque samples were collected from 21 patients with adult periodontitis (AP), 8 with rapidly progressive periodontitis (RPP) and 15 healthy individuals. RESULTS: The frequency detected in culture was as follows: B. forsythus was found in 47.6% of AP sites and in 37.5% of RPP sites. P. gingivalis was identified in 64.3% of AP and 59.4% of RPP sites. A. actinomycetemcomitans was detected in 4.8% of AP and 3.1% of RPP sites. The 3 species were detected in only 2 of the healthy individuals. The proportion of B. forsythus in the total microflora in culture was 0.07% in the healthy group, 4.1% in AP and 2.4% in RPP. The proportions of P. gingivalis were 0% in the healthy group, 18.8% in AP and 16.2% in RPP. The proportion of A. actinomycetemcomitans was very low in all 3 groups. A DNA probe detected B. forsythus in 78.6% of AP and 65.6% of RPP sites, as well as P.gingivalis in 58.3% of AP and 59.4% of RPP sites. A. actinomycetemcomitans was detected in only 1.2% of AP sites. The 3 species were undetectable in the healthy group. CONCLUSIONS: The prevalence and the proportion of B. forsythus and P. gingivalis were significantly correlated with clinical parameters, suggesting that B. forsythus and P. gingivalis are closely related to AP and RPP in the Japanese population.     

Management strategies for achalasia

Treatment options for achalasia include oral pharmacologic therapy, endoscopic injection of botulinum toxin, pneumatic dilation, and myotomy (conventionally by laparoscopy, but more recently by an endoscopic approach). Oral pharmacologic agents have fallen out of use because of insufficient efficacy and frequent side effects. Endoscopic injection of botulinum toxin is safe and has good short‐term effectiveness, but as the effect invariably wears off after a few months, this treatment is reserved for patients who are not candidates for more definitive treatments. Pneumatic dilation and surgical myotomy are currently considered the most effective treatments, with similar effectiveness in randomized controlled trials with follow‐up of up to 2 years. The risk/benefit ratio and choice of therapy depend on patient characteristics (age, comorbidities, disease stage, prior treatments), patient's preference, and locally available expertise. Treatment of patients who fail or relapse after initial therapy is challenging and the success rate of pneumatic dilation or myotomy in this group is lower compared with previously untreated patients. The recently developed peroral endoscopic approach to myotomy has achieved excellent results in early uncontrolled studies, but high‐quality randomized trials are needed to ensure widespread adoption is reasonable. Finally, retrospective data suggest that achalasia subtypes as defined by high‐resolution esophageal pressure topography may guide treatment choice, but confirmation in prospective outcome studies is awaited.