EXTENDED REPORTS

One-year follow-up of Coll2-1, Coll2-1NO₂ and myeloperoxydase serum levels in osteoarthritis patients after hip or knee replacement

M Deberg¹, J-E Dubuc², A Labasse¹, C Sanchez¹, E Quettier², A Bosseloir³, J-M Crielaard¹, Y Henrotin¹

¹ Bone and Cartilage Research Unit, Department of Physical Medicine, University of Liège, CHU, Sart Tilman, B-4000 Liège, Belgium
² Hospital Princess Paola, B-6900 Marche-en-Famenne, Belgium
³ Zentech SA, Liège, Belgium

Y Henrotin, Bone and Cartilage Unit Research, University of Liège, Sart Tilman, B-4000 Liège, Belgium; yhenrotin{at}ulg.ac.be

Objectives: To determine Coll2-1, Coll2-1NO₂ and myeloperoxydase (MPO) levels in serum of patients with knee or hip osteoarthritis (OA) before the surgery, 3 months and 1 year after knee or hip replacement.

Methods: Coll2-1, Coll2-1NO₂ and MPO were measured in 103 patients with isolated symptomatic knee or hip OA candidates for joint replacement. Sera were taken the day before surgery, 3 months and 1 year after hip or knee replacement. Coll2-1 and Coll2-1NO₂ immunohistochemistry was performed on biopsies removed from cartilage lesions.

Results: Immunostainings revealed the extensive presence of Coll2-1 and Coll2-1NO₂ in the superficial layer of fibrillated cartilage and around some chondrocytes clusters. Three months after joint replacement, Coll2-1 and MPO serum levels were decreased and even reached the reference value for Coll2-1. By contrast, Coll2-1NO₂ levels remained elevated. At 1-year follow-up, Coll2-1 levels remained at the reference value, MPO levels were similar to those measured at 3 months, and Coll2-1NO₂ levels were unchanged and comparable to the pre-surgery values. However, in patients with pre-surgery values above the median (more than 0.42 nM), Coll2-1NO₂ levels significantly and progressively decreased post-operatively, but tended towards an increase in patients with pre-surgery Coll2-1NO₂ values below the median.

Conclusions: The normalisation of Coll2-1 levels 3 months after surgery indicates that Coll2-1 is a disease-specific marker that is sensitive to the structural changes occurring in a single joint. Furthermore, the immunohistochemical findings are consistent with the concept that the major source of serum Coll2-1 is the damaged articular cartilage. Finally, serum MPO levels decreased after joint replacement indicating that neutrophil activation occurs in OA joints, even in the late stage of the disease.

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