Aggregatibacter actinomycetemcomitans is frequently associated with localized aggressive periodontitis (LAP); however, longitudinal cohort studies relating A. actinomycetemcomitans to initiation of LAP have not been reported. A periodontal assessment was performed on 1,075 primarily African-American and Hispanic schoolchildren, ages 11 to 17 years. Samples were taken from each child for A. actinomycetemcomitans. A cohort of 96 students was established that included a test group of 38 A. actinomycetemcomitans-positive students (36 periodontally healthy and 2 with periodontal pockets) and 58 healthy A. actinomycetemcomitans-negative controls. All clinical and microbiological procedures were repeated at 6-month intervals. Bitewing radiographs were taken annually for definitive diagnosis of LAP. At the initial examination, clinical probing attachment measurements indicated that 1.2% of students had LAP, while 13.7% carried A. actinomycetemcomitans, including 16.7% of African-American and 11% of Hispanic students (P ‫؍‬ 0.001, chi-square test). A. actinomycetemcomitans serotypes a, b, and c were equally distributed among African-Americans; Hispanic students harbored predominantly serotype c (P ‫؍‬ 0.05, chi-square test). In the longitudinal phase, survival analysis was performed to determine whether A. actinomycetemcomitans-positive as compared to A. actinomycetemcomitansnegative students remained healthy ("survived") or progressed to disease with attachment loss of >2 mm or bone loss (failed to "survive"). Students without A. actinomycetemcomitans at baseline had a significantly greater chance to remain healthy (survive) compared to the A. actinomycetemcomitans-positive test group (P ‫؍‬ 0.0001). Eight of 38 A. actinomycetemcomitans-positive and none of 58 A. actinomycetemcomitans-negative students showed bone loss (P ‫؍‬ 0.01). A. actinomycetemcomitans serotype did not appear to influence survival. These findings suggest that detection of A. actinomycetemcomitans in periodontally healthy children can serve as a risk marker for initiation of LAP.

c Aggregatibacter actinomycetemcomitans-induced localized aggressive periodontitis (LAP) in African-American adolescents has been documented but is poorly understood. Two thousand fifty-eight adolescents aged 11 to 17 years were screened for their periodontal status and the presence of A. actinomycetemcomitans in their oral cavity. Seventy-one A. actinomycetemcomitansnegative and 63 A. actinomycetemcomitans-positive periodontally healthy subjects were enrolled, sampled, examined, and radiographed yearly for 3 years. Gingival and periodontal pocket depth and attachment levels were recorded. Disease presentation was characterized by bone loss (BL). Subgingival sites were sampled every 6 months to assess (i) the role of A. actinomycetemcomitans in BL and (ii) the association of A. actinomycetemcomitans and other microbes in their relationships to BL. Sixteen of 63 subjects with A. actinomycetemcomitans developed BL (the other 47 subjects with A. actinomycetemcomitans had no BL). No A. actinomycetemcomitans-negative subjects developed BL. Human oral microbe identification microarray (HOMIM) was used for subgingival microbial assessment. On a subject level, pooled data from A. actinomycetemcomitans-positive subjects who remained healthy had higher prevalences of Streptococcus and Actinomyces species, while A. actinomycetemcomitans-positive subjects with BL had higher prevalences of Parvimonas micra, Filifactor alocis, A. actinomycetemcomitans, and Peptostreptococcus sp. human oral taxon 113 (HOT-113). At vulnerable sites, A. actinomycetemcomitans, Streptococcus parasanguinis, and F. alocis levels were elevated prior to BL. In cases where the three-organism consortium (versus A. actinomycetemcomitans alone) was detected, the specificity for detecting sites of future BL increased from 62% to 99%, with a sensitivity of 89%. We conclude that detecting the presence of A. actinomycetemcomitans, S. parasanguinis, and F. alocis together indicates sites of future BL in LAP. A synergistic interaction of this consortium in LAP causation is possible and is the subject of ongoing research.

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.

Improved diagnostics remains a fundamental goal of biomedical research. This study was designed to assess cytokine biomarkers that could predict bone loss (BL) in localized aggressive periodontitis. 2,058 adolescents were screened. Two groups of 50 periodontally healthy adolescents were enrolled in the longitudinal study. One group had Aggregatibacter actinomycetemcomitans (Aa), the putative pathogen, while the matched cohort did not. Cytokine levels were assessed in saliva and gingival crevicular fluid (GCF). Participants were sampled, examined, and radiographed every 6 months for 2–3 years. Disease was defined as radiographic evidence of BL. Saliva and GCF was collected at each visit, frozen, and then tested retrospectively after detection of BL. Sixteen subjects with Aa developed BL. Saliva from Aa-positive and Aa-negative healthy subjects was compared to subjects who developed BL. GCF was collected from 16 subjects with BL and from another 38 subjects who remained healthy. GCF from BL sites in the 16 subjects was compared to healthy sites in these same subjects and to healthy sites in subjects who remained healthy. Results showed that cytokines in saliva associated with acute inflammation were elevated in subjects who developed BL (i.e., MIP-1α MIP-1β IL-α, IL-1β and IL-8; p<0.01). MIP-1α was elevated 13-fold, 6 months prior to BL. When MIP-1α levels were set at 40 pg/ml, 98% of healthy sites were below that level (Specificity); whereas, 93% of sites with BL were higher (Sensitivity), with comparable Predictive Values of 98%; p<0.0001; 95% C.I. = 42.5–52.7). MIP-1α consistently showed elevated levels as a biomarker for BL in both saliva and GCF, 6 months prior to BL. MIP-1α continues to demonstrate its strong candidacy as a diagnostic biomarker for both subject and site vulnerability to BL.

No abstract