The Development of Salivary Biomarkers to Detect Systemic Diseases
Chamindie Punyadeera,
Associate Professor/Head/Saliva Translational Research Group,
Queensland University of Technology
It is now becoming evident that there is a strong association between oral and systemic diseases. Human saliva has gained attention as the diagnostic fluid of the future. Human saliva functions as a plasma ultra-filtrate and contains 2,340 proteins that are either transported across blood into salivary glands or produced by the salivary glands. The collection of saliva is less invasive compared with taking a blood sample making it very accessible to both patients and clinicians. Saliva is also a medium that is ideal for large population-based screening and potentially provides healthcare systems a more economical approach to detecting HF within the community.
Within our team, we are using saliva as a biological matrix to detect ischemic heart disease and heart failure. We used AlphaLISA® technology to quantify C-Reactive Protein levels in saliva samples collected from controls and cardiac patients. The mean CRP levels in the saliva of controls was 285 pg/mL and in cardiac patients was 1680 pg/mL (p<0.01). Analysis of CRP concentrations in paired serum and saliva samples from cardiac patients gave a positive correlation (r2 = 0.84, p < 0.001) and the salivary CRP concentration capable of distinguishing healthy from diseased patients. Similarly, salivary NT-proBNP levels in the healthy controls and HF participants were <16 pg/mL and 76.8 pg/mL, respectively. The salivary NT-proBNP immunoassay showed a clinical sensitivity of 82.2% and specificity of 100%, positive predictive value of 100% and negative predictive value of 83.3%, with an overall diagnostic accuracy of 90.6%.
Saliva is in close proximity to head and neck cancer, especially oral cavity cancers and by analysing salivary DNA methylation and miRNA signatures, we have been able to detect these cancers. DNA methylation, addition of methyl groups to CpG promoter sites and the changes of methylation is a hall mark of cancer. We have identified common tumour suppressor genes to be methylated in saliv
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