Chondrocyte, Disc, and Tendon Biology
Change in proteoglycan metabolism is a characteristic of human patellar tendinopathy
Article first published online: 7 JUN 2010
Copyright © 2010 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 62, Issue 10, pages 3028–3035, October 2010
How to Cite
Parkinson, J., Samiric, T., Ilic, M. Z., Cook, J., Feller, J. A. and Handley, C. J. (2010), Change in proteoglycan metabolism is a characteristic of human patellar tendinopathy. Arthritis & Rheumatism, 62: 3028–3035. doi: 10.1002/art.27587
- Issue published online: 7 JUN 2010
- Article first published online: 7 JUN 2010
- Accepted manuscript online: 7 JUN 2010 12:00AM EST
- Manuscript Accepted: 25 MAY 2010
- Manuscript Received: 11 MAR 2010
- Faculty of Health Sciences, La Trobe University
- La Trobe University postgraduate award (LTA Scholarship)
To determine differences in the metabolism of proteoglycans and the gene expression of proteinases and their inhibitors between patellar tendons exhibiting chronic overuse tendinopathy and normal patellar tendons in humans.
Rates of loss and synthesis of proteoglycans were determined. Radiolabeled and total proteoglycans retained in and lost from the tissue were analyzed by fluorography and Western blotting. Levels of messenger RNA for matrix metalloproteinase 1 (MMP-1), MMP-2, MMP-3, MMP-9, MMP-13, ADAMTS-1, ADAMTS-4, ADAMTS-5, tissue inhibitor of metalloproteinases 1 (TIMP-1), TIMP-2, TIMP-3, and TIMP-4 were determined in fresh tissue.
The rate of loss of 35S-labeled proteoglycans was greater in abnormal tendons, as was the rate of synthesis of proteoglycans. Fluorography and Western blotting revealed the presence of greater amounts of large proteoglycans (aggrecan and versican) in abnormal tendons, and these proteoglycans were rapidly lost from the matrix of abnormal tendons. There was no significant difference in the expression of ADAMTS-1, ADAMTS-4, ADAMTS-5, MMP-1, MMP-2, MMP-3, MMP-13, TIMP-2, TIMP-3, or TIMP-4. There was a significant increase in the expression of MMP-9 and TIMP-1 in abnormal tendons.
Our findings suggest that a change in the proteoglycan content of the extracellular matrix in abnormal tendons results from the altered metabolism of the cells, reflected in the enhanced synthesis of the large proteoglycans aggrecan and versican, and does not appear to result from changes at the level of gene expression.