INHIBITION OF CARTILAGE DEGRADATION AND CHANGES IN PHYSICAL-PROPERTIES INDUCED BY IL-1-BETA AND RETINOIC ACID USING MATRIX METALLOPROTEINASE INHIBITORS

Bovine cartilage explants were treated with 100 ng/ml recombinant huma n interleukin-1 beta (IL-1 beta) or 1 mu M all-trans retinoic acid (RA ) and changes in biochemical, biomechanical, and physicochemical prope rties were assessed. Additionally, samples cultured with IL-1 beta or RA were treated with 4 mu M recombinant human tissue inhibitor of meta lloproteinases-l (TIMP-1) or a synthetic metalloproteinase inhibitor ( L-758,354) to inhibit this degradation. Treatment with IL-1 beta or RA each resulted in >90% GAG loss after 8 days in culture. Addition of T IMP or L-758,354 to the culture media inhibited IL-1 beta-induced loss of tissue GAG by 40 and 65%, respectively, and inhibited RA-induced G AG loss by 35 and 65%, respectively. Analysis of degradation products in the culture media using a G1 antibody indicated that IL-1 beta- and RA-treated plugs released 68-kDa fragments of aggrecan, corresponding to a segment of the aggrecan core protein from the G1 domain to the C -terminus NITEGE, consistent with ''aggrecanase'' activity. Release of the G1 fragment was inhibited by treatment with L-758,354. Both IL-1 beta and RA induced significant loss of hyaluronan from cartilage expl ants after 8 days of exposure and HA loss was also inhibited by additi on of L-756,354 to the culture media, IL-1 beta, but not RA, induced a significant increase in swelling ratio (wet weight in 0.01 M NaCl nor malized to wet weight in DMEM) after 8 days in culture, consistent wit h degradation of the collagen network, and the increase in tissue swel ling was inhibited by treatment with TIMP-1 or L-758,354. Exposure to IL-1 beta or RA resulted in significant changes in cartilage physical properties including streaming potential, equilibrium modulus, hydraul ic permeability, and electrokinetic coupling coefficient after 8 days in culture, and these changes were inhibited by 40-90% by exposure to TIMP and by 50-90% by exposure to L-758,354. Measurement of dynamic st reaming potential showed that changes due to treatment with IL-1 beta alone were highly dependent in compression frequency, with dramatic ch anges seen at high frequency prior to changes in mechanical properties , and little initial change seen at low frequency. Streaming potential and equilibrium modulus of explants treated with RA decreased to 10% of their initial values after 8 days in culture, but decreased to only 40 and 90%, respectively, when treated with RA plus TIMP-1. (C) 1997 Academic Press.