Introduction: Osteoarthritis (OA) is a degenerative joint disease partially mediated by the catabolic cytokine TNF-α, leading to progressive and permanent degeneration of cartilage. Silymarin, an extract from the ripe seeds of Silybum marianum, possesses anti-inflammatory properties that could help resolve inflammation in chondrocytes. This study aims to assess the chondroprotection and anti-inflammatory effects of silymarin on TNF-α induced cell death, pro-inflammatory cytokine and matrix-metalloproteinase release. Methods: Human C-20/A4 chondrocytic cells were treated with silymarin (2–20 μM) alone or in the presence of dexamethasone (10 μM) for 30 min prior to TNF-α (60 pg/ml) stimulation for 6 h. Cell viability was determined by MTT assat. Cell free supernatants were collected to detect IL-6, IL-8 and MMP-1 release by ELISA. RT-PCR was used to detect IL-6, IL-8 and MMP-1 gene expression. Data are expressed as Mean ± SD of n = 4 determinations in triplicate.
< 0.05 vs. control or #P < 0.05 vs. stimulus. Results: TNF-α stimulation caused a maximal cell death of 25%, which was completely abrogated in the presence of silymarin (2 μM) and dexamethasone (10 μM). TNF-α caused a significant increase in IL-6, IL-8 and MMP-1 release, which was inhibited by silymarin. RT-PCR analysis confirmed that silymarin alone and in the presence of dexamethasone significantly inhibited IL-6, IL-8 and MMP-1 gene expression when compared to TNF-α (IL-6: 5.79 ± 0.05; IL-8: 5.65 ± 0.04; and MMP-1: 10.0 ± 0.04). Conclusion: The data demonstrates that silymarin exhibited chondroprotection and modulation of IL-6, IL-8 and MMP-1 following TNF-α activation of chondrocytes. This data highlights a role for silymarin in exerting its anti-inflammatory and chondroprotective properties in osteoarthritic models.