MIP-1a: A Salivary Biomarker in Aggressive Periodontitis

Objectives: The presence of Aggregatibacter actinomycetemcomitans (Aa) in healthy children was shown to relate to the initiation of periodontal bone loss in a longitudinal cohort study. This study was designed to determine whether cytokines/chemokines detected in the saliva of healthy children 6-9 months prior to bone loss could be considered as relevant biomarkers of disease initiation. Methods: 1,200 children from Newark were assessed for periodontal attachment levels and the presence of Aa. Saliva and dental plaque was sampled and stored for future analysis. A cohort of periodontally healthy Aa-positive and Aa-negative students were re-examined and radiographs were taken at regular intervals. Of students followed for > 1 year, 21 cytokines/chemokines were analyzed in the saliva of Aa-positive students prior to bone loss and compared to Aa-positive and Aa-negative students who remained healthy. Results: 19 cytokines were either undetected or detected at low levels. 6 of 7 Aa-positive students had elevated MIP-1a 6 to 9 months prior to bone loss, as compared to 7 Aa-positive and 7 Aa-negative students who remain healthy (p<0.001). IL-1b was also somewhat elevated (not significant). Subsequently, saliva from another 21 Aa-negative and 13 Aa-positive were compared to the Aa-positive bone loss group. Significant elevations were now found in both IL-1b (p<0.001) and MIP-1a (p<0.0001). Conclusions: Two cytokines, MIP-1a and IL-1b, were elevated in saliva 6 to 9 months prior to detection of Aa-related aggressive bone loss in adolescence. Since both MIP-1a and IL-1b have been implicated in osteoclastic activation, their detection in saliva could serve as potentially useful surrogate bio-markers of early stages of periodontal bone loss.