Serum Levels of Coll2-1, a Specific Biomarker of Cartilage Degradation, Are Not Affected by Sampling Conditions, Circadian Rhythm, and Seasonality.

OBJECTIVE: To assess intraindividual biological variability of serum cartilage specific biomarker Coll2-1 and define the best standardized conditions for blood sampling. DESIGN: Blood samples were taken from 116 subjects with knee osteoarthritis (OA) at a single time point (PRODIGE study) and from 15 healthy subjects under various conditions, including fasting condition, sampling time and season, blood treatment, and type of blood collection tube (COVAR study). Type II collagen-specific biomarker Coll2-1 was directly measured in serum using an immunoassay. RESULTS: There was no significant difference on Coll2-1 values between samples collected at any of the 5 sampling times or at any of the sampling days measured. None of the sampling parameters tested had a significant impact on Coll2-1 value (clotting time, clotting temperature and temperature of blood centrifugation, type of tube). On the contrary, differences were found in between subjects and between subjects with knee OA and healthy subjects. CONCLUSION: Coll2-1 measurement is not affected by sampling specific conditions, circadian rhythm or seasons but was found elevated in subject with knee OA indicating that Coll2-1 serum variation is not linked to the study environment, but to cartilage degradation in OA. Coll2-1 assay is sufficiently robust for use in OA clinical trials.

Collagen catabolism through Coll2-1 and Coll2-1NO2 and myeloperoxidase activity in marathon runners.

To determine the influence of marathon on the serum levels of two markers of cartilage degradation, Coll2-1 and its nitrated form, Coll2-1NO2, and of a marker of neutrophils activation, the myeloperoxidase (MPO). Coll2-1, Coll2-1NO2, total and active MPO were measured in 98 marathon runners without joint pain and with an average age of 47 years. Sera were taken at rest right before the departure and within 30 min after the marathon. The subjects were submitted to a questionnaire concerning their physical activity and their life style. The levels of Coll2-1, Coll2-1NO2 and active MPO were not affected by age, body mass index, sex or performance. The levels of total MPO were higher in female than in male (p < 0.05), but were not affected by the other parameters. After the marathon, Coll2-1 and Coll2-1NO2 concentrations were slightly but systematically decreased. The total and active MPO concentrations were increased by 2 to 3-fold in comparison to the pre-marathon values (p < 0.001 for total and active MPO). The active MPO/total MPO ratio was significantly enhanced after the marathon (p < 0.001). The variation of total MPO during the marathon was negatively correlated with the training time per week (r = -0.34; p = 0.009). The serum levels of Coll2-1 and Coll2-1NO2 were slightly decreased by marathon, indicating that intensive running could reduce cartilage catabolism. Furthermore, Coll2-1NO2 was not correlated with the total and active MPO indicating that Coll2-1 nitration did not result of a systemic oxidative phenomenon but reflects local changes.

New serum biochemical markers (Coll 2-1 and Coll 2-1 NO2) for studying oxidative-related type II collagen network degradation in patients with osteoarthritis and rheumatoid arthritis.

OBJECTIVE: Protein nitration is a prominent feature of inflammatory processes in the joint. We have developed immunoassays specific for a peptide of the alpha-helical region of type II collagen 108HRGYPGLDG116 (Coll 2-1) and its nitrated form 108HRGY(NO2)PGLDG116 (Coll 2-1 NO2) in biological fluids. DESIGN: Coll 2-1 and Coll 2-1 NO2 peptides were injected into rabbits. Two antisera (D3 and D37) were selected for their specificity and affinity and used to develop specific immunoassays. Coll 2-1 and Coll 2-1 NO2 were measured in sera of 242 healthy subjects (N), 67 patients with primary knee osteoarthritis (OA) and 19 patients with rheumatoid arthritis (RA). RESULTS: In healthy subjects, Coll 2-1 and Coll 2-1 NO2 concentrations were 125.13+/-3.71 nM and 0.16+/-0.08 nM, respectively. In OA and RA, Coll 2-1 and Coll 2-1 NO2 serum levels were found to be significantly increased compared to controls of the same range of age (Coll 2-1: OA: 200.80+/-8.98 nM, RA: 172.30+/-19.05 nM, normal: 126.60+/-6.70 nM and Coll 2-1 NO2: OA: 0.26+/-0.02, RA: 0.38+/-0.05, normal: 0.12+/-0.01 nM). Coll 2-1 NO2 levels were significantly more elevated in RA than in OA patients (P<0.05). As a consequence, the ratio Coll 2-1 NO2/Coll 2-1 was 1.6 times higher in RA than in OA subjects. No relationship was found between the radiological OA severity and the levels of Coll 2-1 and Coll 2-1 NO2 in serum. Coll 2-1 NO2, but not Coll 2-1, was correlated with C-reactive protein in the sera of OA and RA patients. CONCLUSIONS: The determination of both Coll 2-1 and Coll 2-1 NO2 in serum of arthritic patients seems to be a promising useful tool for the detection of oxidative-related cartilage degradation episode. Further, these markers could be helpful for monitoring the effects of anti-inflammatory or antioxidant drugs on cartilage degradation.