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Open Access Research article

Synovial membrane protein expression differs between juvenile idiopathic arthritis subtypes in early disease

Sorcha Finnegan1, Joanne Robson2, Caitriona Scaife3, Catherine McAllister4, Stephen R Pennington3, David S Gibson15* and Madeleine E Rooney14

Author Affiliations

1 Arthritis Research Group, Queen’s University Belfast, Centre for Infection and Immunity, Health Sciences Building, 97 Lisburn Road, Belfast BT9 7BL, UK

2 School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK

3 Proteome Research Centre, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Dublin Ireland

4 Pediatric Rheumatology, Withers Ward, Musgrave Park Hospital, 20 Stockman's Lane, Belfast BT9 7JB, UK

5 Northern Ireland Centre for Stratified Medicine, C-TRIC Building, Altnagelvin Hospital campus, Glenshane Road, Londonderry BT47 6SB, UK

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Arthritis Research & Therapy 2014, 16:R8  doi:10.1186/ar4434

Published: 13 January 2014

Abstract

Introduction

Juvenile idiopathic arthritis (JIA) is the most common rheumatological disease of childhood with a prevalence of around 1 in 1,000. Without appropriate treatment it can have devastating consequences including permanent disability from joint destruction and growth deformities. Disease aetiology remains unknown. Investigation of disease pathology at the level of the synovial membrane is required if we want to begin to understand the disease at the molecular and biochemical level. The synovial membrane proteome from early disease-stage, treatment naive JIA patients was compared between polyarticular and oligoarticular subgroups.

Methods

Protein was extracted from 15 newly diagnosed, treatment naive JIA synovial membrane biopsies and separated by two dimensional fluorescent difference in-gel electrophoresis. Proteins displaying a two-fold or greater change in expression levels between the two subgroups were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry with expression further verified by Western blotting and immunohistochemistry.

Results

Analysis of variance analysis (P ≤ 0.05) revealed 25 protein spots with a two-fold or greater difference in expression levels between polyarticular and oligoarticular patients. Hierarchical cluster analysis with Pearson ranked correlation revealed two distinctive clusters of proteins. Some of the proteins that were differentially expressed included: integrin alpha 2b (P = 0.04); fibrinogen D fragment (P = 0.005); collagen type VI (P = 0.03); fibrinogen gamma chain (P = 0.05) and peroxiredoxin 2 (P = 0.02). The identified proteins are involved in a number of different processes including platelet activation and the coagulation system.

Conclusions

The data indicate distinct synovial membrane proteome profiles between JIA subgroups at an early stage in the disease process. The identified proteins also provide insight into differentially perturbed pathways which could influence pathological events at the joint level.