MIP-1a: An Early Indicator of LAP Periodontal Site Breakdown Risk

Objectives: Localized Aggressive Periodontitis (LAP) is often discovered in pre-teens and teenagers only after radiographic evidence of alveolar bone loss or tooth mobility is seen.  Demographic data indicates that African-American and Hispanic young individuals are particularly at risk.  There is a need to find early biomarkers of tooth sites at risk for periodontal breakdown in these populations.  This study investigated 21 cytokines associated with osteoclastic activity to determine if any can serve as an early biomarker of sites at risk for periodontal breakdown.  Methods: Sixty-nine (69) subjects from an ongoing longitudinal study of consented Newark, NJ schoolchildren, ages 10-17 had 3mls of unstimulated saliva sampled at six month intervals.  The subjects were categorized as to periodontal status (pocket depths, attachment loss and radiographs).  Saliva was clarified by centrifugation and stored at -80•C until analyzed.  Luminex multibead analysis of 21 cytokines (IFN-gamma, IL-1a, IL-1b, IL-2, IL-3, IL-4,  Il-6, IL-7, IL-8, IL-10, IL-12(p40), IL-12(p70), IL-13, IL-17, MCP-1, MCP-3, MIP-1a, MIP-1b, RANTES, TNF-a, TNF-b) of all salivary samples was performed in duplicate.  Data was analyzed by ANOVA and Tukey-Kramer HSD pair-wise comparisons to determine significant differences in cytokine levels versus periodontal status.  Results: Four cytokines, IL-1b, MIP-1a, MIP-1b and IL-12(p40) appeared to have statistically higher (p≤0.05) salivary levels six months to 1 year prior to radiographic evidence of breakdown.  MIP-1a demonstrated the greatest differences (Healthy Subjects (n=41) 18.7±20.4 ng/ml, Potential Disease (6mm pockets) Subjects (n=18),  8.1±10.9 ng/ml, Breakdown Subjects Before Breakdown (n=10), 126±71.5 ng/ml, Breakdown Subjects After Breakdown (n=10), 9.9±11.5 ng/ml).  The other 3 cytokines demonstrated a similar pattern but smaller differences.  Conclusions: Salivary MIP-1a levels are significantly elevated 6 months-1 year prior to LAP breakdown.  This cytokine may be a candidate biomarker for early risk of periodontal breakdown in LAP.