Effects of three avocado/soybean unsaponifiable mixtures on metalloproteinases, cytokines and prostaglandin E2 production by human articular chondrocytes

The in-vitro effects of avocado and soybean unsaponifiable residues on neutral metalloproteinase activity, cytokines and prostaglandin E₂ (PGE₂) production by human articular chondrocytes were investigated. Avocado and soybean unsaponifiable residues were mixed in three ratios: 12 (A1S2), 21 (A2S1) or 11 (A2S2). Freshly isolated human chondrocytes were cultured for 72 h in the absence or presence of interleukin-1 (IL-1) (17 ng/ml), with or without unsaponifiable residue mixtures at a concentration of 10 g/ml. A/S unsaponifiable residues were also tested separately at concentrations of 3.3, 6.6 and 10 g/ml. All A/S unsaponifiable mixtures reduced the spontaneous production of stromelysin, interleukin-6 (IL-6), interleukin-8 (IL-8) and prostaglandin E₂ (PGE₂) by chrondrocytes. At concentrations of 3.3 and 6.6 g/ml, A/S residues, tested separately, were potent inhibitors of the production of IL-8 and PGE₂. Nevertheless, only avocado residue inhibited IL-6 production at these concentrations. A/S unsaponifiable mixtures had a more pronounced inhibitory effect on cytokine production than avocado or soybean residues added alone. As anticipated, IL-1 induced a marked release of collagenase, stromelysin, IL-6, IL-8 and PGE₂. A/S unsaponifiable mixtures partially reversed the IL-1 effects on chrondrocytes. These findings suggest a potential role for A/S unsaponifiable extracts in mitigating the deleterious effects of IL-1 on cartilage.