Salivary transcriptome biomarkers: For the identification of periodontitis susceptibility.

Abstract

Periodontitis (gum disease) is a chronic infectious disease affecting the supporting tissue around the teeth. Bacteria cause the infection and subsequently activate the natural inflammatory host response. The response to bacterial infection varies between individuals. Epidemiological studies have shown that only a minority of the population are susceptible to advanced chronic periodontitis while the majority of the population have mild to moderate forms of the disease. Identifying individuals who are susceptible to periodontitis will enable focused patient management and timely preventive programs. A readily available and non-invasive source of potential biomarkers is saliva. The “salivary transcriptome” defines the RNA present in saliva. Significant changes to the salivary transcriptome of oral cancer patients have been described previously. The aim of this study was to discover potential biomarkers of susceptibility with the identification of mRNAs that are differentially expressed in the saliva of healthy and chronic periodontitis patients. Using an Oragene® RNA kit total RNA was purified from the saliva of 10 chronic periodontitis patients and 10 with healthy or only mildly inflamed gingivae (the health/gingivitis group). The quantity and quality of the total RNA was determined, and a measure of gene expression via cDNA was undertaken using the Affymetrix Microarray system. The microarray profiling result was further validated by real-time quantitative PCR. The result showed that there was acceptable quality and quantity of total RNA from saliva but a high proportion of it was of microbial origin and there was insufficient human salivary transcriptome for expression studies. Detecting the human salivary transcriptome is difficult as it is mostly partially fragmented and degraded in saliva. Nevertheless, the prospect of identifying a saliva biomarker in the gene expression profile of susceptible patients is novel however, further work is required to enhance the extraction process of human mRNA from saliva.