OBJECTIVE: To determine whether load-induced injury causes alterations in proteoglycan (PG), stromelysin-1 (MMP-3) and collagen in articular cartilage. METHODS: Mature bovine cartilage was cyclically loaded at 0.5 Hz with 1 and 5 MPa for 1, 6 and 24h. Immediately after loading explants were evaluated for cell viability. Alterations in matrix integrity were determined by measuring PG content, PG degradation using 7D4 and 3B3(-) antibodies, broken collagen using COL2-3/4m antibody, and stromelysin-1 content using a MMP-3 antibody. RESULTS: Mechanical load caused cell death and PG loss starting from the articular surface and increasing in depth with loading time. There was a decrease in the 7D4 epitope (native chondroitin sulfate) in the superficial zone of cartilage loaded for longer than 1h, but an increase around chondrocytes in the deep zone. The 3B3(-) staining for degraded/abnormal chondroitin-4-sulfate neoepitope appeared only in cartilage loaded under the most severe condition (5 MPa, 24 h). The elevation of stromelysin-1 was co-localized with broken collagen (COL2-3/4m) at the articular surface in explants loaded with 1 and 5 MPa for 24 h. CONCLUSIONS: Cell death and PG loss occurred within 6h of cyclic loading. The elevation of MMP-3 following cell death was consistently found in the superficial zone of loaded cartilage. Since MMP-3 can degrade PG and super-activate procollagenase, the increase of MMP-3 can therefore induce matrix degradation and PG depletion in mechanically injured articular cartilage, both of which are important to the development of osteoarthritis.
OBJECTIVE: To determine whether load-induced injury causes alterations in proteoglycan (PG), stromelysin-1 (MMP-3) and collagen in articular cartilage. METHODS: Mature bovinecartilage was cyclically loaded at 0.5 Hz with 1 and 5 MPa for 1, 6 and 24h. Immediately after loading explants were evaluated for cell viability. Alterations in matrix integrity were determined by measuring PG content, PG degradation using 7D4 and 3B3(-) antibodies, broken collagen using COL2-3/4m antibody, and stromelysin-1 content using a MMP-3 antibody. RESULTS: Mechanical load caused cell death and PG loss starting from the articular surface and increasing in depth with loading time. There was a decrease in the 7D4 epitope (native chondroitin sulfate) in the superficial zone of cartilage loaded for longer than 1h, but an increase around chondrocytes in the deep zone. The 3B3(-) staining for degraded/abnormal chondroitin-4-sulfate neoepitope appeared only in cartilage loaded under the most severe condition (5 MPa, 24 h). The elevation of stromelysin-1 was co-localized with broken collagen (COL2-3/4m) at the articular surface in explants loaded with 1 and 5 MPa for 24 h. CONCLUSIONS: Cell death and PG loss occurred within 6h of cyclic loading. The elevation of MMP-3 following cell death was consistently found in the superficial zone of loaded cartilage. Since MMP-3 can degrade PG and super-activate procollagenase, the increase of MMP-3 can therefore induce matrix degradation and PG depletion in mechanically injured articular cartilage, both of which are important to the development of osteoarthritis.
Authors: Gregory D Jay; Braden C Fleming; Bryn A Watkins; Karen A McHugh; Scott C Anderson; Ling X Zhang; Erin Teeple; Kimberly A Waller; Khaled A Elsaid Journal: Arthritis Rheum Date: 2010-08
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Authors: Yulia Shifrin; Pamela D Arora; Yasutaka Ohta; David A Calderwood; Christopher A McCulloch Journal: Mol Biol Cell Date: 2009-01-14 Impact factor: 4.138