PRTN3 and rheumatoid arthritis: Bivariate correlation analysis revealed that ACPA levels, apart from positively correlating with CRP levels, a well-known marker to assess systemic inflammation (57), was found to be positively related with levels of sTWEAK and sCD163 in serum, indicating that these two biomarkers might be good preclinical inflammatory status indicators for early RA patients, corroborating previous findings on both biomarkers in established RA (15, 18).