Deutsch O et al. Identification of Sjögren's syndrome oral fluid biomarker candidates following high-abundance protein depletion. Rheumatology (Oxford). 2015 May;54(5):884-90. Epub 2014 Oct 21. PMID: 25339641.
Rheumatology (Oxford). 2015 May;54(5):884-90. doi: 10.1093/rheumatology/keu405. Epub 2014 Oct 21.
Identification of Sjögren's syndrome oral fluid biomarker candidates following high-abundance protein depletion.
Deutsch O(1), Krief G(1), Konttinen YT(2), Zaks B(1), Wong DT(1), Aframian DJ(1), Palmon A(3).
OBJECTIVE: SS is an autoimmune exocrinopathy affecting ∼1 million patients in the USA that is diagnosed mostly in middle-aged women. Oral fluids (OFs) serving as the mirror of the body were suggested as an ideal non-invasive diagnostic tool. Previously we developed depletion techniques for OF high-abundance proteins to increase visualization of low-abundance proteins. Therefore the aim of this study was to examine the effect of depletion pretreatments on the identification potential of SS OF biomarker candidates.
METHODS: Unstimulated OFs were collected from 18 female SS 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 liquid chromatography tandem mass spectrometry (LC-MS/MS). To initially validate the MS results, western blotting was performed.
RESULTS: The use of depletion strategy before proteomics analysis increased identification ability by 3-fold. Overall, 79 biomarker candidates were identified. Proteins with the most pronounced fold changes were related to SS serum or tissue factors. In addition, bioinformatics analysis of proteins with a >3-fold increase in SS patients showed calcium-binding proteins, defence-response proteins, proteins involved in apoptotic regulation, stress-response proteins and cell motion-related proteins. Preliminary validation by western blotting of profilin and CA-I indicated similar expression profile trends to those identified by quantitative MS.
CONCLUSION: The significance of OF novel depletion methodologies is clearly demonstrated for increased visibility of biomarker candidates 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.
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PMID: 25339641 [PubMed - indexed for MEDLINE]