The human oral metaproteome reveals potential biomarkers for caries disease

Tooth decay is considered the most prevalent human disease worldwide. We present the first metaproteomic study of the oral biofilm, using different mass spectrometry approaches that have allowed us to quantify individual peptides in healthy and caries-bearing individuals. A total of 7771 bacterial and 853 human proteins were identified in 17 individuals, which provide the first available protein repertoire of human dental plaque. Actinomyces and Coryneybacterium represent a large proportion of the protein activity followed by Rothia and Streptococcus. Those four genera account for 60-90% of total diversity. Healthy individuals appeared to have significantly higher amounts of L-lactate dehydrogenase and the arginine deiminase system, both implicated in pH buffering. Other proteins found to be at significantly higher levels in healthy individuals were involved in exopolysaccharide synthesis, iron metabolism and immune response. We applied multivariate analysis in order to find the minimum set of proteins that better allows discrimination of healthy and caries-affected dental plaque samples, detecting seven bacterial and five human protein functions that allow determining the health status of the studied individuals with an estimated specificity and sensitivity over 96%. We propose that future validation of these potential biomarkers in larger sample size studies may serve to develop diagnostic tests of caries risk that could be used in tooth decay prevention.