Identification of parotid salivary biomarkers in Sjogren's syndrome by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry and two-dimensional difference gel electrophoresis.

Abstract

OBJECTIVES: To identify the most significant salivary biomarkers in Sjögren's syndrome (SS) using proteomic methods. METHODS: Parotid saliva from 20 non-SS subjects and 41 primary SS patients was analysed. Protein expression profiles for each sample were generated by surface-enhanced laser desorption/ionization time-of-flight-mass spectrometry (SELDI-TOF-MS). Mean peak intensities of SS patients and non-SS subjects were compared by univariate analyses. Samples pooled by diagnosis (SS and non-SS) and labelled with different Cy dyes were compared by two-dimensional difference gel electrophoresis (2D-DIGE). Two protein levels that were most significantly different by SELDI-TOF-MS and 2D-DIGE were validated by enzyme-linked immunosorbent assay in individual samples. RESULTS: SELDI-TOF-MS of 10-200 kDa peaks revealed eight peaks with >2-fold changes in the SS group that differed from non-SS at P < 0.005. Peaks of 11.8, 12.0, 14.3, 80.6 and 83.7 kDa were increased, while 17.3, 25.4, and 35.4 kDa peaks were decreased in SS samples. 2D-DIGE identified significant increases of beta-2-microglobulin, lactoferrin, immunoglobulin (Ig) kappa light chain, polymeric Ig receptor, lysozyme C and cystatin C in all stages of SS. Two presumed proline-rich proteins, amylase and carbonic anhydrase VI, were reduced in the patient group. Three of these ten biomarkers have not been associated previously with SS. CONCLUSIONS: The salivary proteomic profile of SS is a mixture of increased inflammatory proteins and decreased acinar proteins when compared with non-SS. Future studies will test the ability of these biomarker levels, alone and in combination, to diagnose the salivary component of SS.

Authors

Ryu, O H; Atkinson, Jane; Hoehn, G T; Illei, G G; Hart, T C;

Keywords

  • Amylases/ analysis
  • Biomarkers/ analysis
  • Carbonic Anhydrases/ analysis
  • Case-Control Studies
  • Cystatin C
  • Cystatins/ analysis
  • Electrophoresis, Gel, Two-Dimensional/ methods
  • Humans
  • Lactoferrin/ analysis
  • Muramidase/ analysis
  • Parotid Gland
  • Protein Subunits/ analysis
  • Proteomics
  • Receptors, Polymeric Immunoglobulin/ analysis
  • Saliva/ chemistry
  • Sjogren's Syndrome/ diagnosis
  • Sjogren's Syndrome/ metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/ methods
  • Statistics, Nonparametric
  • beta 2-Microglobulin/ analysis

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