Osteoarthritis-related fibrosis is associated with both elevated pyridinoline cross-link formation and lysyl hydroxylase 2b expression

D F G Remst; E N Blaney Davidson; E L Vitters; A B Blom; R Stoop; J M Snabel; R A Bank; W B van den Berg; P M van der Kraan

doi:10.1016/j.joca.2012.10.002

Osteoarthritis-related fibrosis is associated with both elevated pyridinoline cross-link formation and lysyl hydroxylase 2b expression

Osteoarthritis Cartilage. 2013 Jan;21(1):157-64. doi: 10.1016/j.joca.2012.10.002. Epub 2012 Oct 13.

Authors

D F G Remst¹, E N Blaney Davidson, E L Vitters, A B Blom, R Stoop, J M Snabel, R A Bank, W B van den Berg, P M van der Kraan

Affiliation

¹ Rheumatology Research and Advanced Therapeutics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. D.Remst@reuma.umcn.nl

PMID: 23069856
DOI: 10.1016/j.joca.2012.10.002

Abstract

Objective: Fibrosis is a major contributor to joint stiffness in osteoarthritis (OA). We investigated several factors associated with the persistence of transforming growth factor beta (TGF-β)-induced fibrosis and whether these factors also play a role in OA-related fibrosis.

Design: Mice were injected intra-articularly (i.a.) with an adenovirus encoding either TGF-β or connective tissue growth factor (CTGF). In addition, we induced OA by i.a. injection of bacterial collagenase into the right knee joint of C57BL/6 mice. mRNA was isolated from the synovium for Q-PCR analysis of the gene expression of various extracellular matrix (ECM) components, ECM degraders, growth factors and collagen cross-linking-related enzymes. Sections of murine knee joints injected with Ad-TGF-β or Ad-CTGF or from experimental OA were stained for lysyl hydroxylase 2 (LH2). The number of pyridinoline cross-links per triple helix collagen in synovium biopsies was determined with high-performance liquid chromatography (HPLC).

Results: Expression of collagen alpha-1(I) chain precursor (Col1a1), tissue inhibitor of metalloproteinases 1 (TIMP1) and especially procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2b (Plod2b) were highly upregulated by TGF-β but not by CTGF. Elevated expression of Plod2b mRNA was associated with high lysyl hydroxylase 2 (LH2) protein staining after TGF-β overexpression and in experimental OA. Furthermore, in experimental OA the number of hydroxypyridinoline cross-links was significant increased compared to control knee joints.

Conclusions: Our data show that elevated LH2b expression is associated with the persistent nature of TGF-β-induced fibrosis. Also in experimental OA, LH2b expression as well as the number of hydroxypyridinoline cross-link were significantly upregulated. We propose that LH2b, and the subsequent increase in pyridinoline cross-links, is responsible for the persistent fibrosis in experimental OA.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acids / metabolism*
Animals
Arthritis, Experimental
Chromatography, Liquid
Collagen / genetics
Collagen / metabolism
Connective Tissue Growth Factor / pharmacology
Extracellular Matrix / genetics
Fibrosis
Gene Expression
Intercellular Signaling Peptides and Proteins / genetics
Intercellular Signaling Peptides and Proteins / metabolism
Mice
Mice, Inbred C57BL
Osteoarthritis, Knee / metabolism*
Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase / metabolism*
RNA Stability
Stifle / pathology
Synovial Membrane / metabolism
Synovial Membrane / pathology*
Transforming Growth Factor beta / pharmacology

Substances

Amino Acids
Intercellular Signaling Peptides and Proteins
Transforming Growth Factor beta
Connective Tissue Growth Factor
pyridinoline
Collagen
Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase
lysyl hydroxylase 2, mouse