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Presence of small proteoglycan fragments in normal and arthritic human cartilage
P Witsch-Prehm1, R Miehlke, H Kresse
1Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Germany.
Objective:
To characterize the small proteoglycans decorin and biglycan in normal human patellar cartilage and in cartilage from individuals with chronic polyarthritis.
Methods:
Cartilage extracts were chromatographed on DEAE-Trisacryl and further separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis before and after enzymatic degradation of the glycosaminoglycan chains. Decorin and biglycan were visualized after Western blotting, using core protein-specific polyclonal and monoclonal antibodies.
Results:
Core protein fragments of both proteoglycans were observed even in normal cartilage. In the case of decorin they amounted to up to 15% of the immunoreactive material, and up to 5% of the core protein was glycosaminoglycan free. The quantity of decorin core protein was reduced in arthritic cartilage, but the core protein fragments represented up to 45% of the immunoreactive material. Different zones of cartilage differed in their content of the fragments. Evidence for an increased proportion of biglycan fragments was not obtained.
Conclusion:
Chronic polyarthritis leads to increased degradation of small proteoglycans. A considerable proportion of decorin fragments is retained in the tissue. These alterations may have a negative influence on the mechanical stability of tissue.