Junichi Mega

Protective immunity to Streptococcus mutans induced by nasal vaccination with surface protein antigen and mutant cholera toxin adjuvant.

In this study, mice were immunized nasally with surface protein antigen of Streptococcus mutans serotype c (PAc) and a nontoxic A subunit mutant of cholera toxin (mCT) E112K, as a mucosal adjuvant. Immunization with PAc and mCT elicited significant PAc-specific secretory IgA in saliva and in nasal secretions. Antibody-forming cell (AFC) analysis confirmed the antibody (Ab) titers by revealing significant numbers of PAc-specific IgA AFCs in the submandibular gland and nasal passages. Furthermore, CD4(+) T cells from cervical lymph nodes exhibited significant proliferative responses when restimulated with PAc in vitro. Importantly, mice that were nasally immunized with PAc plus mCT E112K exhibited significantly reduced oral colonization by S. mutans. These results show that nasal administration of PAc and mCT E112K is potentially an effective mucosal vaccine against dental caries and reduces the colonization of S. mutans in the oral cavity.

Enhancement of lipopolysaccharide-stimulated cyclooxygenase-2 mRNA expression and prostaglandin E2 production in gingival fibroblasts from individuals with Down syndrome.

It is well known that Down syndrome (DS) is a premature ageing syndrome. Periodontal disease in individuals with DS develops rapidly and extensively in a relatively younger age bracket compared with that in healthy controls. The mechanisms involved in the periodontal inflammatory processes in DS patients are not fully understood. In the present study, the non-inflamed gingival fibroblasts isolated from seven patients with DS (DGF) and seven healthy controls (NDGF) were stimulated with lipopolysaccharide (LPS) derived from Actinobacillus actinomycetemcomitans (A. a.). We measured the level of prostaglandin E2 (PGE2) production by DGF and NDGF by radioimmunoassay, and also measured the mRNA expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) by using the real-time PCR method. We found the higher levels of LPS-stimulated COX-2 mRNA expression and PGE2 production in DGF when compared with those in NDGF. This study may indicate that overexpression of LPS-stimulated COX-2 induced a greater ability of DGF to produce PGE2, and that these phenomena may be responsible for the severer periodontal disease in DS patients.

Microbial Flora in Periodontal Pockets Involved with Occlusal Trauma.

The purpose of this study was to clarify the relationship between the frequency of Gram-negative anaerobic black-pigmented rods and periodontal disease-inducing occlusal trauma. The occlusal trauma group had a markedly higher level of gingival exudates and higher numbers of bacteria in gingival exudates than the normal control group. The rate of total numbers of bacteria against a definite amount of gingival exudates were found remarkably higher in all subjects with occlusal trauma than normal controls. Facultative anaerobes showed the highest frequency, in which the Gram-positive coccamount isolation rate of bacteria was predominant in all subjects. The frequency of obligate anaerobes increased in the group with occlusal trauma. The frequency of obligate anaerobic Gram-negative rods was observed to have no significant difference between occlusal trauma and normal control groups. All obligate anaerobic Gram-negative black-pigmented rods in the periodontal pockets isolated from patients with occlusal trauma and normal controls were identified with Prevotella intermedia by a biochemical test. Prevalence of obligate anaerobic Gram-negative black-pigmented rods isolated from occlusal trauma maintained a low level throughout the experimental period. These results indicate that alveolar bone loss in occlusal trauma may have no relation to obligate anaerobic Gram-negative black-pigmented rods.

Microflora in patients treated with fixed prosthetic appliances. Supragingival plaque formed on the full cast crown fabricated with platinum gold cast alloy.

Culture method was used to survey the microflora in supragingival marginal plaque formed on the full cast crown fabricated with platinum gold cast alloy. A band of plaque approximately two millimeters coronal to marginal gingiva in buccal surface was collected from tooth (control group) and full cast crown (experimental group) fabricated with platinum gold cast alloy in mandibular first molar in each subject.The resuls indicated that there was no difference in the bacterial composition, but that there was a difference in the bacterial proportion between two groups. Experimental group had a significantly higher level of Streptococcus and a lower level of Actinomyces and Veillonella in the microbial proportion than control group. But experimental group had not significantly higher level of Streptococcus in the viable counts per wet weight of plaque than control group. This study suggested that physico-chemical properties had the influence upon the microbial ecology in the process of the plaque formation.