A Staphylococcus aureus factor exclusively removes large proteoglycan monomers from explants of articular cartilage

Exposure of explants of viable, as well as freeze-thawed, bovine articular cartilage to culture filtrates of Staphylococcus aureus increased the release of proteoglycans from the tissue significantly within 24 h. The S. aureus factor exclusively releases the large, 4 M guanidinium extractable proteoglycans from the matrix; the small proteoglycans are not affected by this factor. The large proteoglycans, released by Staphylococcal culture filtrate, had a slightly smaller hydrodynamic volume compared to the proteoglycans remaining in the matrix. Purified large proteoglycans, incubated in S. aureus filtrate, lost their capacity to aggregate with hyaluronic acid. This suggests that some culture filtrates of S. aureus contain a factor that degrades the core protein of the large proteoglycans at or near the hyaluronic acid binding region.