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A multidisciplinary approach to study a couple of monozygotic twins discordant for the chronic fatigue syndrome: a focus on potential salivary biomarkers

Federica Ciregia1, Laura Giusti1, Ylenia Da Valle1, Elena Donadio1, Arianna Consensi2, Camillo Giacomelli2, Francesca Sernissi2, Pietro Scarpellini2, Fabrizio Maggi3, Antonio Lucacchini1* and Laura Bazzichi2

Author Affiliations

1 Department of Pharmacy, University of Pisa, Via Bonanno 6, Pisa, 56126, Italy

2 Department of clinical and experimental medicine, Division of Rheumatology, University of Pisa, Via Roma 67, Pisa, 56126, Italy

3 Virology Unit, Pisa University Hospital, Via Roma 67, Pisa, 56126, Italy

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Journal of Translational Medicine 2013, 11:243  doi:10.1186/1479-5876-11-243

Published: 2 October 2013

Abstract

Background

Chronic Fatigue Syndrome (CFS) is a severe, systemic illness characterized by persistent, debilitating and medically unexplained fatigue. The etiology and pathophysiology of CFS remains obscure, and diagnosis is formulated through the patient’s history and exclusion of other medical causes. Thereby, the availability of biomarkers for CFS could be useful for clinical research. In the present study, we used a proteomic approach to evaluate the global changes in the salivary profile in a couple of monozygotic twins who were discordant for CFS. The aim was to evaluate differences of salivary protein expression in the CFS patient in respect to his healthy twin.

Methods

Saliva samples were submitted to two-dimensional electrophoresis (2DE). The gels were stained with Sypro, and a comparison between CFS subject and the healthy one was performed by the software Progenesis Same Spot including the Analysis of variance (ANOVA test). The proteins spot found with a ≥2-fold spot quantity change and p<0.05 were identified by Nano-liquid chromatography electrospray ionization tandem mass spectrometry. To validate the expression changes found with 2DE of 5 proteins (14-3-3 protein zeta/delta, cyclophilin A, Cystatin-C, Protein S100-A7, and zinc-alpha-2-glycoprotein), we used the western blot analysis. Moreover, proteins differentially expressed were functionally analyzed using the Ingenuity Pathways Analysis software with the aim to determine the predominant canonical pathways and the interaction network involved.

Results

The analysis of the protein profiles allowed us to find 13 proteins with a different expression in CFS in respect to control. Nine spots were up-regulated in CFS and 4 down-regulated. These proteins belong to different functional classes, such as inflammatory response, immune system and metabolism. In particular, as shown by the pathway analysis, the network built with our proteins highlights the involvement of inflammatory response in CFS pathogenesis.

Conclusions

This study shows the presence of differentially expressed proteins in the saliva of the couple of monozygotic twins discordant for CFS, probably related to the disease. Consequently, we believe the proteomic approach could be useful both to define a panel of potential diagnostic biomarkers and to shed new light on the comprehension of the pathogenetic pathways of CFS.

Keywords:
Chronic fatigue syndrome; Whole saliva; Proteomics; Two-dimensional electrophoresis