Data in support of Proteomic analysis of synovial fluid from rheumatic arthritis and spondyloarthritis patients

Objective. To analyse the pathogenesis of the diseases rheumatoid arthritis (RA) and spondyloarthritis (SpA) we investigated the protein composition in synovial fluid from the patients. Methods. Fifty-six synovial fluid (SF) were analysed with non-gel based proteomics from patients with RA (32) and SpA (24). Rheumatoid factor was measured in plasma, and cell-free DNA was measured in SF. Results. Two hundred proteins were quantified in the samples. The inflammatory proteins were more abundant in the RA group, specially proteins from neutrophil granulocytes. Cell-free DNA (cfDNA) in the SF was statistically associated with proteins that are known to form neutrophil extracellular traps (NETs). Plasma C-reactive protein (CRP), was correlated to other acute phase proteins in the SF. Minimal correlation was seen between acute phase proteins and proteins in NETs. Conclusions. The results show that in the synovial cavity in vivo neutrophils form NETs. This result sustains that neutrophils from RA patients are activated and are likely to undergo NETosis resulting in SF cfDNA specific of arthritis pathology with NETosis.