Oral-fluids (OF) serving as the "mirror of body" were suggested as an ideal noninvasive diagnostics tool. Previously, we have developed OF high-abundance-proteins depletion techniques to increase visualization of low-abundance-proteins.
Objectives: To characterize OF proteome SjS patients following the removal of high abundant proteins and to establish a panel of biomarkers for the early detection and monitoring of SjS.
Methods: Unstimulated saliva was collected from 18 female SjS patients and 18 healthy age and gender matched controls. High-abundance proteins were depleted using affinity and immunodepletion methodologies followed by semi-quantitative two-dimensional-gel-electrophoresis and quantitative dimethylation LC-MS/MS.
Results: The use of depletion strategy before proteomics analysis increased identification ability by 3 fold. Overall, 79 biomarkers candidates were identified. Proteins with the most pronounced fold changes found were related to SjS serum or tissue factors though, never found in OF before. In addition, bioinformatics analysis of proteins with over threefold increase in SjS patients showed calcium-binding proteins, defense-response proteins, proteins involved in apoptotic regulation, stress-response proteins and cell motion-related proteins.
Conclusion: The significance of OF novel depletion methodologies is clearly demonstrated for increased biomarker candidates’ visibility, as well as for unveiling possible mechanisms involved in this syndrome. This represents a major contribution to our ability to use OF as a future diagnostic fluid.