Identification of psoriatic arthritis mediators in synovial fluid by quantitative mass spectrometry

Daniela Cretu; Ioannis Prassas; Punit Saraon; Ihor Batruch; Rajiv Gandhi; Eleftherios P Diamandis; Vinod Chandran

doi:10.1186/1559-0275-11-27

Identification of psoriatic arthritis mediators in synovial fluid by quantitative mass spectrometry

Clin Proteomics. 2014 Jul 1;11(1):27. doi: 10.1186/1559-0275-11-27. eCollection 2014.

Authors

Daniela Cretu¹, Ioannis Prassas¹, Punit Saraon¹, Ihor Batruch², Rajiv Gandhi³, Eleftherios P Diamandis⁴, Vinod Chandran⁵

Affiliations

¹ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada ; Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada.
² Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada.
³ Arthritis Program, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room 1E 416, Toronto, ON M5T 2S8, Canada ; Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Canada.
⁴ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada ; Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada ; Department of Clinical Biochemistry, University Health Network, Toronto, Ontario, Canada.
⁵ Arthritis Program, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room 1E 416, Toronto, ON M5T 2S8, Canada ; Psoriatic Arthritis Program, Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, Toronto, Ontario, Canada ; Division of Rheumatology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada.

Abstract

Background: Synovial fluid (SF) is a dynamic reservoir for proteins originating from the synovial membrane, cartilage, and plasma, and may therefore reflect the pathophysiological conditions that give rise to arthritis. Our goal was to identify and quantify protein mediators of psoriatic arthritis (PsA) in SF.

Methods: Age and gender-matched pooled SF samples from 10 PsA and 10 controls [early osteoarthritis (OA)], were subjected to label-free quantitative proteomics using liquid chromatography coupled to mass spectrometry (LC-MS/MS), to identify differentially expressed proteins based on the ratios of the extracted ion current of each protein between the two groups. Pathway analysis and public database searches were conducted to ensure these proteins held relevance to PsA. Multiplexed selected reaction monitoring (SRM) assays were then utilized to confirm the elevated proteins in the discovery samples and in an independent set of samples from patients with PsA and controls.

Results: We determined that 137 proteins were differentially expressed between PsA and control SF, and 44 were upregulated. The pathways associated with these proteins were acute-phase response signalling, granulocyte adhesion and diapedesis, and production of nitric oxide and reactive oxygen species in macrophages. The expression of 12 proteins was subsequently quantified using SRM assays.

Conclusions: Our in-depth proteomic analysis of the PSA SF proteome identified 12 proteins which were significantly elevated in PsA SF compared to early OA SF. These proteins may be linked to the pathogenesis of PsA, as well serve as putative biomarkers and/or therapeutic targets for this disease.

Keywords: Early osteoarthritis; Mass spectrometry; Mediators; Proteins; Proteomics; Psoriatic arthritis; Selected reaction monitoring assays; Synovial fluid.