Salivary diagnostics: enhancing disease detection and making medicine better

Abstract

To monitor health status, disease onset and progression, and treatment outcome non-invasively is a most desirable goal in the health care delivery and health research. There are three prerequisites necessary to reach this goal: 1. A non-invasive method for collecting biological samples. 2. Specific biomarkers associated with health or disease. 3. A technology platform to rapidly discriminate the biomarkers. An initiative catalysed by the National Institute of Dental and Craniofacial Research (NIDCR) has created a roadmap to achieve this goal through the use of oral fluids as the diagnostic medium to scrutinize the health and disease status. This is an ideal opportunity to bridge state-of-the-art saliva-based biosensors and disease-discriminatory salivary biomarkers in diagnostic applications. Oral fluid, often called the mirror of the body, is a perfect medium to be explored for health and disease surveillance. The translational applications and opportunities are enormous. This review presents the translational value of saliva as a credible clinical diagnostic fluid and the scientific rationale for such use.

Fig. 1

Anatomical locations of the three major salivary glands: parotid, submandicular and sublingual.

Fig. 2

Mechanisms of transport of proteins and ions from serum into salivary gland ducts.

Fig. 3

Disease markers manifestation in saliva and their detection by saliva diagnostic biosensors (Oral Fluid NanoSensor Test, OFNASET).

Fig. 4

Receiver operator characteristic (ROC) curve analysis for the predictive power of combined salivary mRNA biomarkers. The final logistic model included four salivary mRNA biomarkers, IL1B, OAZ1, SAT and IL8. Using a cut-off probability of 50%, we obtained sensitivity of 91% and specificity of 91% by ROC. The calculated area under the ROC curve was 0.95.

Fig. 5

UCLA's Oral Fluid NanoSensor Test (OFNASET).

Fig. 6

A drop of saliva harbours a world of diagnostic information, proteomically and genomically. A handful of these analytes mark human diseases with great sensitivity and specificity.