Saliva protein profiling for subject identification and potential medical applications

• Salivary proteome has a fraction of proteins showing inter-individual variability. • Age-dependent and -independent factors influence the salivary proteome. • Individual variability results in a salivary proteome useful for identification. This pilot study delineates a protocol to select a set of salivary proteins to distinguish objectively among individual donors. A small subset of proteins (<10%) of > 900 identified by mass spectrometry from wet saliva samples allowed to discriminate among donors supporting the notion that most of the salivary proteome is highly conserved across subjects. Most of these discriminating proteins were involved with immunity, tissue metabolism and regeneration. They were already identified in other saliva proteome studies including those performed with dry saliva samples indicating the likelihood of using wet or dry saliva biospecimens. The differences in the proteomes across subjects may reflect a combination of different lifestyle habits, environmental factors, underlying diseases/conditions, and the many other factors that influence the salivary proteome, but not necessarily age. Application of such proteomic analysis has the potential to increase substantially the value of saliva as a source of proteins in forensic evidence. Additionally, these profiles could possibly be used to develop therapies that are personalized to a patient, built off their individual and unique protein compositions.