Synovial fluid survivin and NETs as independent biomarkers in rheumatoid arthritis

To quantify survivin and NETs in synovial fluid (SF) of patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and to assess whether there is a correlation of the quantifications with the exclusion of OA diagnosis and the activity of RA.

We performed a cross-sectional, observational study, in which 32 patients with RA and 16 with OA were included. Clinical and laboratory data were obtained, in addition to routine analysis of SF and the measurement of SF survivin and NETs. RA activity was assessed by DAS28.

Concentrations of survivin (median, 356.9 vs. 49.9 pg/mL; p=0.0006) and NETs (median, 100.7 vs. 49.7 ng/mL; p=0.004) were elevated in the SF of the RA group compared to those of the OA group. ROC curves showed the following values for measurements of survivin and NETs: AUC of 79% and 75% respectively, with sensitivity of 75% and specificity of 78% for both. There was no correlation between survivin and NETs values for both groups, but we found association between SF survivin and serum ACPA for RA patients.

We found an independent association between levels of survivin and NETs in SF with the exclusion of OA diagnosis, but not with RA activity. There was no correlation between survivin and NETs in SF, because we suppose that resistance to apoptosis, mediated by survivin, and NETosis are independently related to the pathophysiology of RA.