Burning-Mouth-Syndrome and Celiac-Disease Oral-Fluids Proteomics Analysis Following Depletion of High-Abundant-Proteins

Objectives: Oral fluids (OF) have been suggested as a source of biomarkers for both oral and systemic conditions, however, the presence of high-abundance-proteins (HAP's) interferes with the detection of lower-abundance biomarkers. Therefore, development of HAP's depletion from OF, is necessary for sensitive bio-marker discovery.
This study objective was to develop HAP's depletion technologies and further, implement them in two disease models; celiac-disease (CeD) as a systemic disease and burning-mouth-syndrome (BMS) as an oral disease.
Methods: Protein profiling of OF samples was performed by 2-DE and quantitative mass spectrometry (q-MS), results were further analyzed by David-Kegg and String bioinformatics tools and biomarkers candidates were preliminary validated.
Results: 108 CeD up-regulated proteins (above twofold increase), and additional 96 CeD novel proteins were identified. Bioinformatics analysis indicated lysosome and proteasome complexes. Preliminary validation, based on luminex multiplexing, showed correlative results to the q-MS. Expression of Elongation factor 2 (accession no. P13639) and Neutrophil collagenase (P22894) were increased by several folds in CeD. Profiling of OF from BMS patient showed 158 up-regulated proteins (above threefold), and 100 BMS novel proteins. High correlation (p-value<0.005) was found between BMS and the neurotrophin signaling pathway. Preliminary validations sustained this finding, showing overexpression of Calmodulin (5.86-fold increase), Rho GDP-dissociation inhibitor 1 (7.46-fold increase) and 14-3-3 protein (14.86-fold increase) in BMS. These proteins participate in neurotrophin signaling pathway via P75 receptor (P75NTR) which mediates mainly neural-apoptosis. This suggest a possible involvement of neurotrophin signaling pathway in BMS pathophysiology by amplifying P75NTR activity which eventually enhance neural apoptosis and reduce the sub-papillary nerve fibers concentration in the oral mucosa.
Conclusions: The significance of OF novel depletion methodologies is clearly demonstrated for increased biomarker candidates’ visibility, as well as for unveiling possible mechanisms involved in CeD and BMS. This represents a major contribution to our ability to use OF as a future diagnostic fluid.