Serum carboxymethyllysine concentration is associated with erosive hand osteoarthritis.

Objective: Carboxymethyllysine (CML) and homocitrulline (HCit) are the products of two non-enzymatic post-translational modifications of protein, a process related to age. We investigated whether serum CML and HCit concentrations were associated with hand osteoarthritis (HOA), especially erosive HOA.
Design: Serum CML and HCit were measured by using liquid chromatography coupled with tandem mass spectrometry at inclusion in 386 patients included in the DIGItal Cohort Design (DIGICOD) cohort. We investigated whether serum CML and/or HCit concentrations were associated with erosive HOA or with HOA clinical and radiological features. Moreover, we compared the tissular concentrations of CML and HCit in OA and non-OA cartilage from proximal interphalangeal and metacarpo-phalangeal (MCP) joints from human cadaveric donors.
Results: Median (IQR) serum CML concentration was lower in patients with erosive HOA than those with non-erosive HOA (178.7 [157.1-208.8] vs 194.7 [168.9-217.1] μmol/mol Lys, P = 0.002), but median HCit concentration did not differ between the groups (193.9 [162.9-232.0] vs 193.9 [155.9-224.6] μmol/mol Lys). Cartilage HCit and CML concentrations were not correlated with clinical features. Serum CML concentration was higher in OA than non-OA MCPs (7.0 vs 4.0 mmol/mol Lys, P = 0.01).
Conclusions: Serum CML concentration was lower in erosive HOA than non-erosive HOA, and cartilage CML concentration was higher in OA than non-OA cartilage. These results encourage further studies to test whether serum CML could be a new prognostic biomarker in HOA.
Competing Interests: Declaration of competing interest JS reports fees from MSD, Pfizer, Abbvie, Fresenius Kabi, BMS, Roche,Chugai, Sandoz, Lilly, Gilead, Novartis, Janssen, Sanofi outside of this work, research grants from Schwa Medico, MSD, BMS and Roche. AC reports fees from Meda pharma, UCB outside of this study. FB reports personal fees from 4P Pharma, 4Moving Biotech, Boehringer, Bone Therapeutics, Bone-Tech, CellProthera, Expanscience, Galapagos, Gilead, Grunenthal, GSK, Merck Sereno, Heel, MSD, Nordic Pharma, Nordic Bioscience, Novartis, Peptinov, Pfizer, Roche, Sandoz, Sanofi, Servier, TRB Chemedica, UCB, Viatris outside the submitted work. ACB, SJ, AO, FE, PG, ST, AM, AR, MDC declare that they have no competing interest.
(Copyright © 2023 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)