Salivary biomarkers: toward future clinical and diagnostic utilities

Abstract

The pursuit of timely, cost-effective, accurate, and noninvasive diagnostic methodologies is an endeavor of urgency among clinicians and scientists alike. Detecting pathologies at their earliest stages can significantly affect patient discomfort, prognosis, therapeutic intervention, survival rates, and recurrence. Diagnosis and monitoring often require painful invasive procedures such as biopsies and repeated blood draws, adding undue stress to an already unpleasant experience. The discovery of saliva-based microbial, immunologic, and molecular biomarkers offers unique opportunities to bypass these measures by utilizing oral fluids to evaluate the condition of both healthy and diseased individuals. Here we discuss saliva and its significance as a source of indicators for local, systemic, and infectious disorders. We highlight contemporary innovations and explore recent discoveries that deem saliva a mediator of the body's physiological condition. Additionally, we examine the current state of salivary diagnostics and its associated technologies, future aspirations, and potential as the preferred route of disease detection, monitoring, and prognosis.

Fig 1

Locations of salivary glands (parotid, submandibular, and sublingual). The image shows a lateral view of the head showing the positions of the major salivary glands (the parotid, submandibular, and sublingual glands) and the nerves charged with their innervation (the trigeminal and facial nerves). Each gland is paired. The parotid glands are located just in front of each ear and are the largest of the three major salivary glands. The submandibular glands reside beneath the lower jaw just posterior and below the sublingual glands, which are located under the tongue. (Reprinted from reference by permission of Mayo Foundation for Medical Education and Research.)

Fig 2

Mechanism of molecular transport from serum into salivary gland ducts. The image shows the proximity of a major salivary gland to the vascular system. Salivary glands are highly vascularized, allowing for the exchange of blood-based constituents. Acinus cells within the salivary glands absorb molecules from the blood and secrete salivary juices into the oral cavity. Alterations in the molecular composition of the blood may subsequently modify the composition of salivary secretions. Disease-specific blood-based biomarkers could sufficiently alter the output of salivary glands, yielding saliva-based biomarkers of systemic disorders. (Reprinted from reference by permission of Mayo Foundation for Medical Education and Research. Adapted from reference .)