Salivary MMP-8 and Antimicrobial Peptides as Biomarkers of Periodontal Disease

Methods: Whole saliva was collected by spitting in 25 subjects with G and 32 with CP. ELISA assays were performed and differences in salivary concentrations of MMP-8 were compared with HNP1-3 and S100A8 in G and CP using ANOVA and ROC curve analysis.    

Results: MMP-8 levels were significantly (p=<0.0001) higher in CP (146.2ng/ml) than in G 11.12ng/ml). There were significant differences in MMP-8 between gingivitis, mild, moderate and severe periodontitis (ANOVA p<0.0001). ROC analysis showed MMP-8 to have a greater area under its curve (AUC) (0.95) compared to HNP1-3 (0.61) and S100A8 (0.71). The optimum diagnostic cut-off for MMP-8 (>24.28ng/ml) showed greater sensitivity and specificity (84.38% and 96.00%) compared with HNP1-3(<0.335; 53.13% and 84.00%) and S100A8 (>137.2; 60% and 76%).  There was no significant correlation in G patients between MMP-8 and HNP1-3 (p=0.5388) or S100A8 (p=0.1675), nor in CP (HNP1-3; p=0.4906 and S100A8;p=0.2692).  Combined, the 3 biomarkers had an AUC of 72.38. Their optimum cut-off (>325.5) showed sensitivity of 70.59% and specificity of 60.87%.

Conclusions: MMP-8 can differentiate between G and CP with high sensitivity and specificity, exceeding the diagnostic ability of the antimicrobial biomarkers HNP1-3 and S100A8. The 3 biomarkers combined did not show greater diagnostic discrimination than they do individually. Lack of significant correlation between the 3 biomarkers suggests they may be measuring different aspects of periodontal disease.  Further analysis will assess whether similar correlations are seen in AgP patients.