Therapeutic potential of COMP and TIMP-3 in preserving cartilage integrity compromised by proteases: A histo-mechanical study

Abstract

Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) significantly impact articular cartilage biomechanical properties in osteoarthritis (OA). However, comprehensive understanding of biomechanical responses and the efficacy of potential therapeutic interventions remains limited. This study investigates how MMPs and ADAMTS synergistically degenerate cartilage biomechanical properties under different loading conditions, and evaluates the preventive role of cartilage oligomeric matrix protein (COMP) and tissue inhibitor of metalloproteinase-3 (TIMP-3). Bovine tibiofemoral cartilage disks (N = 80) with subchondral bone from 8 cows were harvested and incubated with MMP-9, MMP-13, ADAMTS-5, COMP, and TIMP-3 in four distinct combinations: Group A (MMP-9+MMP-13+ADAMTS-5), Group B (Group A + COMP), Group C (Group A + TIMP-3), Group D (Group B + TIMP-3) and Group E (negative control). Comprehensive biomechanical assessment included indentation, unconfined compression, and dynamic testing to simulate various physiological activities. Safranin O and Picrosirius red staining were used for histological analysis. Group A demonstrates reduced Young's modulus $71.7\%\left(95\%\text{confidence}\text{interval}\left(\text{CI}\right):\left[64.3\%,85.2\%\right]\right)$, instantaneous modulus $71.4\%\left(95\%\text{CI}:\left[50.0\%,83.6\%\right]\right)$, and equilibrium modulus $61.7\%\left(95\%\text{CI}:\left[24.6\%,80.6\%\right]\right)$ compared to controls. Adding COMP substantially improved Young's modulus $41.4\%\left(95\%\text{CI}:\left[9.9\%,102.2\%\right]\right)$ and equilibrium modulus $18.9\%\left(95\%\text{CI}:\left[-31.9\%,107.8\%\right]\right)$ relative to Group A. Supplementation with TIMP-3 exhibited significant improvements in strain-dependent instantaneous modulus and dynamic modulus by $235.5\%\left(95\%\text{CI}:\left[117.7\%,417.9\%\right]\right)$ and $178.6\%\left(95\%\text{CI}:\left[100.4\%,296.3\%\right]\right)$ respectively. Histological assessment confirmed improvement in proteoglycan and collagen preservation across treatment groups. This study suggests that COMP helps preserve cartilage mechanical integrity by indirectly protecting cartilage from all the applied proteases, while TIMP-3 provides substantial additional protection through direct inhibition of MMP-13 and ADAMTS-5. The investigations suggest activity-specific recommendations for OA management and provide valuable insights into developing targeted OA interventions.