EXTENDED REPORT

Sequential changes of parathyroid hormone related protein (PTHrP) in articular cartilage during progression of inflammatory and degenerative arthritis

E Gómez-Barrena¹, O Sánchez-Pernaute², R Largo², E Calvo², P Esbrit³, G Herrero-Beaumont⁴

¹ Bone and Joint Research Laboratory, Fundación Jiménez Díaz, and Department of Surgery, Universidad Autónoma, Madrid, Spain
² Bone and Joint Research Laboratory, Fundación Jiménez Díaz, Madrid, Spain
³ Bone and Mineral Research Laboratory, Fundación Jiménez Díaz, Madrid, Spain
⁴ Bone and Joint Research Laboratory, Fundación Jiménez Díaz, and Department of Medicine, Universidad Autónoma, Madrid, Spain

Correspondence to:
Correspondence to:
Professor E Gómez-Barrena
Servicio de Cirugía Ortopédica y Traumatología, Fundación Jiménez Díaz, Avda. Reyes Católicos 2, E-28040 Madrid, Spain; egomez{at}fjd.es

Objective: To investigate immunolocalisation of parathyroid hormone related protein (PTHrP) in two sequential models of experimental cartilage damage (inflammatory and degenerative) in order to elucidate differences in chondrocyte response to the disease.

Methods: Immunohistochemistry with a polyclonal rabbit antiserum to the N-terminal domain of PTHrP was used to detect this protein in two different rabbit models sharing progressive cartilage damage: antigen induced arthritis (AIA) and osteoarthritis (OA) secondary to partial medial meniscectomy. Cartilage specimens from early (2 days in AIA; 8 weeks in experimental OA) and late (3 weeks in AIA; 52 weeks in OA) disease were compared.

Results: Cell and matrix PTHrP staining in early AIA and OA was similar to that in controls. Late AIA cartilage showed a significant decrease in PTHrP positive cells and in the cartilage matrix. In contrast, at late OA stages, distinct PTHrP positivity was detected in proliferating cell clones, as assessed by proliferating cell nuclear antigen staining around cartilage damaged areas.

Conclusion: PTHrP staining of hyaline articular cartilage shows a different pattern during progression of each type of arthritis: an overall decrease associated with the inflammatory disease, and an increase in the proliferating chondrocyte clones with degenerative arthritis.

Abbreviations: AIA, antigen induced arthritis; BSA, bovine serum albumin; OA, osteoarthritis; PBS, phosphate buffered saline; PCNA, proliferating cell nuclear antigen; PTH, parathyroid hormone; PTHrP, parathyroid hormone related protein; RA, rheumatoid arthritis

Keywords: parathyroid hormone related protein; immunohistochemistry; articular cartilage; antigen induced arthritis

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• Godler, D. E., Stein, A. N., Bakharevski, O., Lindsay, M. M. L., Ryan, P. F. J. (2005). Parathyroid hormone-related peptide expression in rat collagen-induced arthritis. Rheumatology (Oxford) 44: 1122-1131 [Abstract] [Full Text]