Biomarkers Identification in Proteins Depleted Oral-Fluids of Sjogren's Syndrome Patients

Oral fluids (OF) are important diagnostic fluids due to their complex mixture. Previous studies found that high abundant proteins depletion, improves visualization of low abundant proteins in OF. SjS is an autoimmune exocrinopathy with a clear female predilection characterized by lymphocytic infiltration to the salivary and lacrimal glands. As no definitive clinical or serological marker for identification is available, there is great need for finding SjS specific biomarkers. Objective: To characterize OF proteins composition of SjS patients, following the removal of three high abundant proteins, utilizing proteomics approaches. Materials and Methods: OF samples were collected from 18 SjS diagnosed patients and from 18 age and gender matched healthy volunteers. The samples were pooled, pretreated with OF high abundant proteins removal devices and analyzed by 2-DE-SDS-PAGE followed by Mass Spectrometry, and by quantitative MS. Results: SjS patient's samples analysis revealed 81 differentially expressed (2-7 fold change) proteins from which 25 proteins were previously reported and 56 proteins were newly reported. Characterization of these proteins according to their biological functions found them related mainly to calcium-biding-proteins defense-response, regulation-of-apoptosis and cell-motion. Conclusion: This research suggests an OF unique protein expression profile of SjS patients. It also indicates the strength of high-abundant-proteins depletion tool to OF proteomics diagnostic approach. Further analysis should be utilized to establish simple, inexpensive, non-invasive screening application for populations at risk for SjS.