Risk of aggressive periodontitis in adolescent carriers of the JP2 clone of Aggregatibacter (Actinobacillus) actinomycetemcomitans in Morocco: a prospective longitudinal cohort study

Feasibility and therapeutic strategies of vaccines against Porphyromonas gingivalis

Periodontitis is a chronic infectious disease that is highly prevalent worldwide and is characterized by inflammation of the gums, and loss of connective tissue and bone support. The Gram-negative anerobic bacterium Porphyromonas gingivalis is generally accepted as the main etiological agent for chronic periodontitis. The objective of this paper is to elucidate the feasibility of achieving protection against periodontitis though immunization against P. gingivalis. Until now, animal studies have showed no complete protection against P. gingivalis. However, current knowledge about P. gingivalis structures could be applicable for further research to develop a successful licensed vaccine and alternative therapeutic strategies. This review reveals that a multicomponent vaccine against P. gingivalis, which includes structures shared among P. gingivalis serotypes, will be feasible to induce broad and complete protection.

Occurrence of Aggregatibacter actinomycetemcomitans in Brazilian Indians from Umutina Reservation, Mato Grosso, Brazil

Aggregatibacter actinomycetemcomitans is associated with periodontal disease, especially localized aggressive periodontitis, produces a potent leukotoxin and its distribution is influenced by ethnic characteristics of the population.

Aggregatibacter actinomycetemcomitans leukotoxin: from threat to therapy

Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium that colonizes the human oral cavity and is the causative agent for localized aggressive periodontitis (LAP), an aggressive form of periodontal disease that occurs in adolescents. A. actinomycetemcomitans secretes a protein toxin, leukotoxin (LtxA), which helps the bacterium evade the host immune response during infection. LtxA is a membrane-active toxin that specifically targets white blood cells (WBCs). In this review, we discuss recent developments in this field, including the identification and characterization of genes and proteins involved in secretion, regulation of LtxA, biosynthesis, newly described activities of LtxA, and how LtxA may be used as a therapy for the treatment of diseases.

Stability of the JP2 Clone of Aggregatibacter actinomycetemcomitans

The JP2 clone of Aggregatibacter actinomycetemcomitans is strongly associated with aggressive periodontitis. To obtain information about colonization dynamics of the JP2 clone, we used PCR to examine its presence in 365 Moroccan juveniles from whom periodontal plaque samples were collected at baseline and after one and two years. Periodontal attachment loss was measured at baseline and at the two-year follow-up. At baseline, 43 (12%) carriers of the JP2 clone were found. Nearly half (44 %) of these were persistently colonized with the clone. The relative risk for the development of aggressive periodontitis, adjusted for the concomitant presence of other genotypes of A. actinomycetemcomitans, was highest for individuals continuously infected by the JP2 clone (RR = 13.9; 95% CI, 9.0 to 21.4), indicating a relationship between infectious dose and disease, which further substantiates the evidence for the JP2 clone as a causal factor in aggressive periodontitis.

Presence of Aggregatibacter actinomycetemcomitans in young individuals: a 16-year clinical and microbiological follow-up study

AIM

To look for clinical signs of periodontal disease in young adults who exhibited radiographic bone loss and detectable numbers of Aggregatibacter actinomycetemcomitans in their primary dentition.

MATERIAL AND METHODS

Periodontal status and radiographic bone loss were examined in each of the subjects 16 years after the baseline observations. Techniques for anaerobic and selective culture, and checkerboard, were used to detect periodontitis-associated bacterial species. The isolated A. actinomycetemcomitans strains were characterized by polymerase chain reaction.

RESULTS

Signs of localized attachment loss were found in three out of the 13 examined subjects. A. actinomycetemcomitans was recovered from six of these subjects and two of these samples were from sites with deepened probing depths and attachment loss. Among the isolated A. actinomycetemcomitans strains, serotypes a-c and e, but not d or f, were found. None of the isolated strains belonged to the highly leucotoxic JP2 clone, and one strain lacked genes for the cytolethal distending toxin.

CONCLUSIONS

This study indicates that the presence of A. actinomycetemcomitans and early bone loss in the primary dentition does not necessarily predispose the individual to periodontal attachment loss in the permanent dentition.

Microbiological profile of untreated subjects with localized aggressive periodontitis

AIM

The microbial profile of localized aggressive periodontitis (LAgP) has not yet been determined. Therefore, the aim of this study was to evaluate the subgingival microbial composition of LAgP.

MATERIAL AND METHODS

One hundred and twenty subjects with LAgP (n=15), generalized aggressive periodontitis (GAgP, n=25), chronic periodontitis (ChP, n=30) or periodontal health (PH, n=50) underwent clinical and microbiological assessment. Nine subgingival plaque samples were collected from each subject and analysed for their content of 38 bacterial species using checkerboard DNA-DNA hybridization.

RESULTS

Red complex and some orange complex species are the most numerous and prevalent periodontal pathogens in LAgP. The proportions of Aggregatibacter actinomycetemcomitans were elevated in shallow and intermediate pockets of LAgP subjects in comparison with those with GAgP or ChP, but not in deep sites. This species also showed a negative correlation with age and with the proportions of red complex pathogens. The host-compatible Actinomyces species were reduced in LAgP.

CONCLUSION

A. actinomycetemcomitans seems to be associated with the onset of LAgP, and Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Campylobacter gracilis, Eubacterium nodatum and Prevotella intermedia play an important role in disease progression. Successful treatment of LAgP would involve a reduction in these pathogens and an increase in the Actinomyces species.

Macrophage inflammatory protein-1alpha: a salivary biomarker of bone loss in a longitudinal cohort study of children at risk for aggressive periodontal disease?

BACKGROUND

Periodontitis develops in a time-dependent manner. Cross-sectional studies document one moment in time but fail to capture the progressive nature of disease. Radiographic measures of bone loss are relatively insensitive but are reliable markers of irreversible disease. Longitudinal studies are needed to identify biomarkers that can precede radiographic evidence of bone loss and, thus, mark the period prior to clinical evidence of irreversible disease. A longitudinal study of students susceptible to localized aggressive periodontitis (LAgP) was conducted to evaluate chemokines/cytokines found in saliva derived from periodontally healthy children who subsequently developed alveolar bone loss.

METHODS

Students were screened, sampled for Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans [Aa]), and divided into a cohort of Aa+ and Aa- students. Ninety-six periodontally healthy Aa+ and Aa- students were recalled every 6 to 9 months following screening. Examinations, saliva collections, and radiographs were performed. After seven students developed bone loss, the levels of 21 cytokines were assessed and matched to saliva from seven Aa+ and seven Aa- students who remained healthy for > or =1 year. Subsequently, saliva from an additional 27 students who remained healthy was analyzed.

RESULTS

Nineteen cytokines were not detected or were detected at low levels. Macrophage inflammatory protein (MIP)-1alpha was elevated 50-fold in seven Aa+ students who developed disease 6 to 9 months prior to radiographic detection of bone loss compared to levels in 21 Aa+ and 20 Aa- students who remained healthy (P <0.001). Interleukin (IL)-1beta was also elevated (P = 0.01). MIP-1alpha had a specificity of 96.8% and a sensitivity of 100%, whereas IL-1beta showed 90.3% specificity and 85.7% sensitivity relative to bone loss. MIP-1alpha levels were also related to increasing probing depth and the number of pockets >6 mm.

CONCLUSION

The superior sensitivity and specificity of MIP-1alpha, which correlated well with probing depths and the onset of bone loss, suggested that it could be used as an early biomarker for LAgP.

Periodontal infectogenomics

Multicellular creatures consist of a symbiosis between the host and its colonizing bacteria. The oral cavity may contain as many as 19,000 bacterial phylotypes, while each individual presents a proportion of these microbes. Infectogenomics studies the interaction between host genetic variations and composition of the microbiota. This review introduces the concept of periodontal infectogenomics, defined as the relationship between host genetic factors and the composition of the subgingival microbiota. In particular, the evidence for the effect of genetic variants in neutrophil and cytokine genes and the presence of periodontopathogenic bacteria will be discussed. The influence of genetic factors may affect clearance or persistence of pathogenic bacteria subgingivally, therefore increasing the risk for the development of common pathogenic conditions such as gingivitis and periodontitis, leading to early tooth loss. Mechanisms of interaction between genetic and microbiological factors and prospects for future studies will be discussed.

Diminished treatment response of periodontally diseased patients infected with the JP2 clone of Aggregatibacter (Actinobacillus) actinomycetemcomitans

This longitudinal study evaluated the response to periodontal treatment by subjects infected with either JP2 (n = 25) or non-JP2 (n = 25) Aggregatibacter (Actinobacillus) actinomycetemcomitans. Participants were treated during the first 4 months by receiving (i) scaling and root planing, (ii) systemic antibiotic therapy, and (iii) periodontal surgery. Probing depth (PD), clinical attachment level (CAL), and gingival and plaque indices (GI and PI, respectively) were monitored at baseline and at 12 months, along with DNA-PCR-based subgingival detection of JP2 or non-JP2 A. actinomycetemcomitans. At baseline, PD, CAL, and GI scores were statistically higher in the JP2 strain-positive group than the non-JP2-strain-positive group. At 12 months, PD, CAL, and GI scores had decreased significantly for both groups, but the reduction rates of PD and CAL were higher in the non-JP2-strain-positive group. Among JP2-strain-positive patients in the baseline, patients who remained JP2 strain positive at 12 months showed significantly higher GIs than did the patients who had lost the detectable JP2 clone. Patients who remained JP2 strain positive at 12 months appeared to be more resistant to mechanical-chemical therapy than did those who were still non-JP2 strain positive, while the elimination of JP2 A. actinomycetemcomitans remarkably diminished gingival inflammation. Early identification and elimination of the JP2 clone of A. actinomycetemcomitans will enable practitioners to effectively predict the outcome of treatments applied to periodontal patients.

Prevalence and distribution of principal periodontal pathogens worldwide

BACKGROUND

Detailed genetic analysis of bacteria has demonstrated an unanticipated genetic diversity within species, which often reveals evolutionary lineages that are disproportionately associated with infection. There is evidence that some evolutionary lineages of bacteria have adapted to particular ethnic groups.

AIM

This review analyzes to what extent observed differences in periodontal disease prevalence among ethnically or geographically distinct populations may be explained by restricted host adaptation of clones of principal periodontal pathogens.

RESULTS

Carriage rates of several putative periodontal pathogens and particular subsets of these species vary between ethnic groups. Few of these differences can, with the limited information available, be directly related to differences in periodontal disease prevalence. Asian populations are regularly colonized with Actinobacillus actinomycetemcomitans serotype c with questionable pathogenic potential. Conversely, the JP2 clone of A. actinomycetemcomitans has enhanced virulence and causes significantly higher prevalence of aggressive periodontitis in adolescents whose descent can be traced back to the Mediterranean and Western parts of Africa. Some genetically distinct types of Porphyromonas gingivalis are more associated with disease than others, but additional work is required to relate this to clinical differences.

CONCLUSIONS

Studies that take into account differences linked to the genetics of both patients and potential pathogens are likely to give better insight into the aetiology of periodontal diseases.

Differences in subgingival microflora of Korean and German periodontal patients

PURPOSE

The goal of this study was to characterize the microbiological profile in samples of subgingival plaque taken from periodontal patients with different ethnic origin.

METHODS

178 patients (n=90 from South Korea and n=88 from Germany; age: 45.4 +/- 10.4 years) were diagnosed with severe generalized periodontitis. In all patients the deepest pocket of each quadrant was sampled for subgingival plaque. The four samples per patient were pooled and subsequently analysed with a 16s-RNA-gene probe test.

RESULTS

Prevalence of Aggregatibacter actinomycetemcomitans was significantly higher in German patients (47.7%) compared to Korean patients (26.7%) (p < 0.01, chi(2)-test). For Tannerella forsythia and porphyromonas gingivalis, differences between Germans and Koreans were not as pronounced. A statistically significant difference could also be found for Treponema denticola (Germans: 95.5%, Koreans: 81.1%, p < 0.01, chi(2)-test). After logarithmic transformation, bacterial counts differed for all microorganisms under investigation between Germans and Koreans, even after using a General Linear Model/Analysis of Covariance (GLM/ANCOVA) to adjust for gender, age, smoking status, pocket probing depths (PPD) of sampled teeth, and gingival bleeding index (GBI).

CONCLUSION

Depending on their ethnic origin, the microbiological profile of pooled subgingival plaque sample seems to differ significantly between patients of Caucasian and Asian ethnic origin.

Novel loop-mediated isothermal amplification method for detection of the JP2 clone of Aggregatibacter actinomycetemcomitans in subgingival plaque

We developed a loop-mediated isothermal amplification method that detects the JP2 clone of Aggregatibacter actinomycetemcomitans, which induces aggressive periodontitis in adolescents of North and West African descents. Being independent of special equipment, this specific and sensitive method offers significant advantages for screening of patients on a population basis and in clinical settings.