Objective: Pentosidine is an advanced glycation endproduct formed by glycosylation and oxidation. Our aim was to develop a means to measure pentosidine in synovial fluid (SF), and to compare its concentration in SF in patients with osteoarthritis (OA) and rheumatoid arthritis (RA), and to investigate the relationship between its concentration in SF and the disease activity of RA.
Methods: SF was collected from knee joints in 31 patients with RA and 40 with OA, who had hydrarthrosis. One patient with RA and 7 with OA who had the complication of diabetes mellitus or chronic renal failure made up the DM/CRF group, and the remaining patients made up the RA group (n = 30) and the OA group (n = 33). Pentosidine was measured by the direct HPLC method with column switching after hydrolysis of SF.
Results: Pentosidine was detected in all SF and was greater in RA (83.9 +/- 46.0 nmol/l, mean +/- SD) than in OA (40.1 +/- 19.6 nmol/l). Three DM/CRF patients undergoing hemodialysis had markedly high pentosidine levels (482.5 +/- 280.8 nmol/l). There was a significant correlation between pentosidine and C-reactive protein (CRP), erythrocyte sedimentation rate, and Lansbury Index (p < 0.01). Patients with RA were divided into high and low activity groups according to the CRP and Lansbury Index. Pentosidine was significantly higher in the high activity group (CRP > or = 2.0 mg/dl and Lansbury Index > or = 50%) than in the low activity group (CRP < 2.0 and/or Lansbury Index < 50) (100.9 +/- 42.8 vs 58.5 +/- 39.6 nmol/; p = 0.0013).
Conclusion: Pentosidine in synovial fluid was higher in RA than in OA. Pentosidine levels in SF were related to the disease activity in RA.