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Progression of attachment loss is strongly associated with presence of the JP2 genotype of Aggregatibacter actinomycetemcomitans: a prospective cohort study of a young adolescent population
Umeå University, Faculty of Medicine, Department of Odontology.
Ghana University.
Umeå University, Faculty of Medicine, Department of Odontology.
Göteborgs Universitet.
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2014 (English)In: Journal of Clinical Periodontology, ISSN 0303-6979, E-ISSN 1600-051X, Vol. 41, no 3, 232-241 p.Article in journal (Refereed) Published
Abstract [en]

AIM: To assess the progression of attachment loss (AL) during a two-year period according to the presence of JP2 and non-JP2 genotypes of A. actinomycetemcomitans in a Ghanaian adolescent population.

METHODS: A total of 500 adolescents (mean age 13.2 years, SD± 1.5) were enrolled in the study. After two years, 397 (79.4%) returned for a periodontal re-examination, including the measurement of AL. The carrier status of the JP2 and non-JP2 genotypes of A. actinomycetemcomitans was evaluated in a baseline examination two years earlier.

RESULTS: Individuals who carried the JP2 genotype of A. actinomycetemcomitans had a significantly increased risk (relative risk (RR) = 7.3) of developing AL ≥ 3 mm. The mean AL at the follow-up and the mean two-year progression of AL was significantly higher in the JP2 genotype-positive group (n=38) compared with the group positive for the non-JP2 genotypes of A. actinomycetemcomitans (n=169), and the group of A. actinomycetemcomitans-negative individuals (n=190). The JP2 genotype was strongly associated with the progression of AL ≥ 3 mm (OR= 14.3). The non-JP2 genotypes of A. actinomycetemcomitans were also, however less pronounced, associated with the progression of AL ≥ 3 mm (OR=3.4).

CONCLUSION: The JP2 genotype of A. actinomycetemcomitans is strongly associated with the progression of AL.

Place, publisher, year, edition, pages
2014. Vol. 41, no 3, 232-241 p.
Keyword [en]
A. actinomycetemcomitans, JP2 genotype, attachment loss, progression, leukotoxin, Ghana, periodontitis, adolescent
National Category
Dentistry
Research subject
Infectious Diseases
Identifiers
URN: urn:nbn:se:umu:diva-83805DOI: 10.1111/jcpe.12209ISI: 000330577300003PubMedID: 24304011OAI: oai:DiVA.org:umu-83805DiVA: diva2:676974
Funder
Swedish Research Council
Available from: 2013-12-08 Created: 2013-12-07 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Exotoxins of Aggregatibacter actinomycetemcomitans and periodontal attachment loss in adolescents
Open this publication in new window or tab >>Exotoxins of Aggregatibacter actinomycetemcomitans and periodontal attachment loss in adolescents
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aggregatibacter actinomycetemcomitans is an oral bacterium that is mainly associated with aggressive forms of periodontitis, which most often starts at an early age. Amongst the virulence factors of A. actinomycetemcomitans, two exotoxins, the leukotoxin (LtxA) and the cytolethal distending toxin (Cdt), are suggested to play an important role in the pathogenicity of aggressive periodontitis. There is also a genetic diversity of the different strains of A. actinomycetemcomitans, and a variation in the ability of different strains to express and release exotoxins has been suggested. Of the different genotypes of A. actinomycetemcomitans, the highly leukotoxic JP2 genotype, which is prevalent in individuals of African origin, seems to be the genotype that is most strongly associated with localized aggressive periodontitis.

This thesis is built upon studies of a West African adolescent population. The aim was to study the virulence characteristics of A. actinomycetemcomitans genotypes with a specific focus on the LtxA and the Cdt in relation to the progression of attachment loss (AL). The specific aim was first, to investigate cross-sectionally the presence of the JP2 and non-JP2 genotypes of A. actinomycetemcomitans in relation to the prevalence of AL and then prospectively to assess the progression of AL in a Ghanaian adolescent population. Second, in clinical isolates of A. actinomycetemcomitans obtained from the participants of the study, the serotypes and the virulence characteristics related to the two exotoxins were studied and associated with the progression of AL at the individual level.

In Paper I, based on the study population consisting of 500 adolescents (mean age 13.2 years; SD ±1.5), it was shown that the overall carrier rate of A. actinomycetemcomitans was high (54.4%) and that the presence of this bacterium was associated with AL ≥ 3 mm. The JP2 genotype was prevalent (8.8%) in this population. In Paper II, 397 (79.4%) of the study participants were periodontally examined again at a 2-year follow-up. The presence of the JP2 genotype of A. actinomycetemcomitans in subgingival plaque was strongly associated with the progression of AL. This study also provided support for an enhanced estimated risk (odds ratio, OR=3.4), though less pronounced, for the progression of AL in individuals positive for the non-JP2 genotypes of A. actinomycetemcomitans.

In Paper III, all three cdt genes (a, b and c) were detected in 79% of the examined A. actinomycetemcomitans isolates, all of which expressed an active toxin. The distribution of the cdt genes showed a serotype-dependent pattern. In particular, the presence of the b serotypes (both JP2 and non-JP2 genotypes) was associated with the disease progression, whereas the expression of Cdt was not particularly related to the disease progression.  In Paper IV, it was shown that the presence of of A. actinomycetemcomitans isolates with high leukotoxicity, also those of the non-JP2 genotypes of A. actinomycetemcomitans, were associated with an increased risk of the progression of AL in relation to the reference group. The main proportion of the serotype b isolates was distributed in the category of highly leukotoxic isolates. The analyses of the non-JP2 genotypes of serotype b indicated a diversity linked to the level of leukotoxicity.

In conclusion, A. actinomycetemcomitans in general was associated with the progression of AL. Individuals with an increased risk of developing progression of AL mainly harboured isolates of A. actinomycetemcomitans with a high leukotoxicity, which suggests that the LtxA is an important virulence factor. Of the two exotoxins, the pathogenic potential was mainly associated with the LtxA, while the role of the Cdt is unclear.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2013. 87 p.
Series
Umeå University odontological dissertations, ISSN 0345-7532 ; 131
Keyword
Aggregatibacter actinomycetemcomitans, periodontal attachment loss, JP2 genotype, non-JP2 genotype, LtxA, Cdt
National Category
Dentistry
Research subject
Infectious Diseases
Identifiers
urn:nbn:se:umu:diva-83986 (URN)978-91-7459-787-5 (ISBN)
Public defence
2014-01-31, Hörsal Betula, Unod L, plan 0, Norrlands Universitetssjukhus, Umeå, 09:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 396022002
Available from: 2013-12-18 Created: 2013-12-12 Last updated: 2013-12-18Bibliographically approved

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