Saliva Biomarkers: The Unsung Hero of Diagnostics

With the advancement in technology, compositional analysis of saliva for diagnosis of various medical conditions has attracted the researchers over the last decade. Monitoring the salivary biomarkers help in early detection of diseases and increase the rate of success of the treatment. Sampling of saliva is safe, simple, cost effective and does not demand an expertise for collection. Therefore, saliva can be an important diagnostic armamentarium for mass screening for a specific disease or in remote areas. However, despite of various research, there are no definite guidelines regarding sensitivity and specificity of salivary diagnostic tools. Health care professionals must go hand in hand with government agencies to develop more research so that a general acceptance can be developed like that of traditional blood/urine analysis. 2. The person collecting sample does not require specialized training. 3. Collection and storage of saliva is cost effective. 4. Saliva sampling can be used for screening large population and in remote areas. 5. Saliva does not clot so allows an ample amount of working time compared to blood. 6. Reduced risk of transmission/cross infection of diseases compared to blood. 7. Saliva sampling can easily be used in uncooperative children or in children with special needs. However, there could be some limitations [8,9] as the salivary flow rate and the method of collection of a sample of saliva might cause variation in levels of bio markers present in it. The amount of salivary secretion is expected to vary for each person under different condition. Drugs, radiation therapy and chemo therapy administered during the treatment of cancer reduce the salivary gland function, and thus, the quality and quantity of saliva. Also, the proteolytic enzyme present in whole saliva may alter the stability of diagnostic biomarkers present in it. Conclusion and Future potential With the advancements in molecular diagnostics, days are not so far when our health status and sampling will be pain free and convenient. However, still the big challenge is to establish a standard, accurate and validated method to identify disease specific markers in saliva. Researchers are working to develop bio sensors capable of identifying salivary bio markers with high sensitivity and specificity [10]. This would be an incredible leap in health sector, reducing the diagnostic burden financially and creating new clinical opportunities of early diagnosis and prompt treatment. Citation: Mishra A (2017) Saliva Biomarkers: The Unsung Hero of Diagnostics. J Mol Genet Med 11: 288 doi:10.4172/1747-0862.1000288 Volume 11 • Issue 3 • 1000288 J Mol Genet Med, an open access journal ISSN: 1747-0862 Page 2 of 2


Introduction
The oral cavity is a dynamic field consisting of multiple structures working in harmony. Saliva, a prime component of the oral cavity, aids in digestion of food through its endogenous enzymes, buffers the salivary pH and facilitates the ionic exchange between oral structures. Metabolites, electrolytes and other biomarkers are passively filtered into the saliva which are in harmony with the systemic and environmental conditions of an individual [1]. The potential of saliva as a biomarker fluid has been transformed by the development of highly sensitive proteomic analysis, which has identified over 2,000 proteins, approximately 25% to 30% of which are shared with blood (Table 1) [2]. Also, the ease of collection, easy storage, non-invasive sampling and possibility of repetition makes saliva an ideal fluid for the screening of diseases.

Saliva: The oral fluid
The normal salivary secretion is 1 to 1.5 liter per day for an adult. Each of the major salivary gland is regulated by autonomic nervous system. The serous portion of salivary gland is innervated by sympathetic system and mucous portion is innervated by both parasympathetic and sympathetic stimulation resulting in secretion of saliva. Parasympathetic stimulation leads to high flow of saliva with less quantity of organic and inorganic compounds. Sympathetic stimulation produces less quantity of protein-rich and potassium-rich saliva [3]. Intake of meal results in an increase of total proteins and of α-amylase in saliva [4].
However, the resultant salivary flow is also influenced by the age, oral hygiene, psychological conditions, nasal and visual stimulation, physical exercise. Thus, the saliva collected from the oral cavity is the complex mixture of secretary product of the three major and numerous minor salivary glands along with mucosal transudate [5], nasal secretion, cellular and food debris [6], oral microbes and various metabolites. The mode of entry of these constituents from the blood into the saliva is by passive intracellular diffusion and active transport or para-cellular routes by extra cellular ultrafiltration within the salivary glands or through gingival tissues [7].

Discussion
Can saliva be an alternative to blood for diagnostic procedures?
1. Collection of saliva is noninvasive procedure when compared to blood sampling. However, there could be some limitations [8,9] as the salivary flow rate and the method of collection of a sample of saliva might cause variation in levels of bio markers present in it. The amount of salivary secretion is expected to vary for each person under different condition. Drugs, radiation therapy and chemo therapy administered during the treatment of cancer reduce the salivary gland function, and thus, the quality and quantity of saliva. Also, the proteolytic enzyme present in whole saliva may alter the stability of diagnostic biomarkers present in it.

Conclusion and Future potential
With the advancements in molecular diagnostics, days are not so far when our health status and sampling will be pain free and convenient. However, still the big challenge is to establish a standard, accurate and validated method to identify disease specific markers in saliva. Researchers are working to develop bio sensors capable of identifying salivary bio markers with high sensitivity and specificity [10]. This would be an incredible leap in health sector, reducing the diagnostic burden financially and creating new clinical opportunities of early diagnosis and prompt treatment.