The influence of decorin, a potential pro-inflammatory stimulant, on the mechanical properties of the annulus fibrosus

This study evaluated whether exposure to decorin (a small leucine-rich proteoglycan and potential ECM-derived DAMP) alters inflammatory signaling and tensile mechanical integrity of the intervertebral disc annulus fibrosus. Rat tail annulus rings were cultured for 6 days in control media or media supplemented with bovine decorin (0.5 or 5 µg/mL). At day 6, IL-6 and MIP-2 were detectable in conditioned media but did not differ significantly between groups, suggesting no sustained dose-dependent cytokine elevation at the measured endpoint. In contrast, decorin exposure altered multiple tensile properties during circumferential ring testing: high-dose decorin increased toe-region strain, initial failure strain, and strain at maximum stress (increased laxity/deformation), and also increased stress at initial failure and maximum stress compared with controls (greater strength), while Young’s modulus was not significantly different between conditions. The authors propose that decorin may drive collagen fiber reorganization (increasing strength) while potentially contributing to non-collagen matrix changes that permit greater deformation, highlighting complex ECM–mechanics relationships relevant to disc degeneration and annular injury susceptibility.