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Esculetin inhibits cartilage resorption induced by interleukin 1alpha in combination with oncostatin M
S Elliott1, A D Rowan, S Carrère
1Department of Rheumatology, Cookson Building, Medical School, Newcastle-upon-Tyne NE2 4HH, UK. s.f.elliot@ncl.ac.uk
Objective:
To determine if a new inhibitor, esculetin (EST), can block resorption of cartilage.
Methods:
Interleukin 1alpha (IL1alpha, 0.04-5 ng/ml) and oncostatin M (OSM, 0.4-50 ng/ml) were used to stimulate the release of proteoglycan and collagen from bovine nasal cartilage and human articular cartilage in explant culture. Proteoglycan and collagen loss were assessed by dimethylmethylene blue and hydroxyproline assays, respectively. Collagenase levels were measured by assay of bioactivity and by enzyme linked immunosorbent assay (ELISA). The effects of EST on the expression of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the transformed human chondrocyte cell line T/C28a4 were assessed by northern blot analysis. TIMP-1 protein levels were assayed by ELISA. The effect of EST on the MMP-1 promoter was assessed using a promoter-luciferase construct in transient transfection studies.
Results:
EST inhibited proteoglycan and collagen resorption in a dose dependent manner with significant decreases seen at 66 microM and 100 microM EST, respectively. Collagenolytic activity was significantly decreased in bovine nasal cartilage cultures. In human articular cartilage, EST also inhibited IL1alpha + OSM stimulated resorption and decreased MMP-1 levels. TIMP-1 levels were not altered compared with controls. In T/C28a4 chondrocytes the IL1alpha + OSM induced expression of MMP-1, MMP-3, and MMP-13 mRNA was reduced to control levels by 250 microM EST. TIMP-1 mRNA levels were unaffected by EST treatment. All cytokine stimulation of an MMP-1 luciferase-promoter construct was lost in the presence of the inhibitor.
Conclusion:
EST inhibits degradation of bovine nasal cartilage and human articular cartilage stimulated to resorb with IL1alpha + OSM.
Insights
Esculetin (EST) effectively inhibits cartilage degradation by blocking proteoglycan and collagen resorption. This new inhibitor shows promise in preventing cartilage breakdown stimulated by inflammatory cytokines.
Area of Science:
- Biochemistry
- Biomedical Engineering
- Cell Biology
Background:
- Cartilage degradation is a hallmark of osteoarthritis, driven by inflammatory cytokines like Interleukin 1alpha (IL1alpha) and Oncostatin M (OSM).
- Matrix metalloproteinases (MMPs) play a crucial role in breaking down cartilage components, including proteoglycans and collagen.
- Identifying inhibitors that can block these degradative pathways is essential for developing treatments for cartilage-related diseases.
Purpose of the Study:
- To investigate the potential of esculetin (EST) as an inhibitor of cartilage resorption.
- To determine the efficacy of EST in blocking the release of proteoglycans and collagen from cartilage explants.
- To elucidate the molecular mechanisms by which EST affects MMP expression and activity.
Main Methods:
- Cartilage explant cultures (bovine nasal and human articular) were stimulated with IL1alpha and OSM to induce resorption.
- Proteoglycan and collagen loss were quantified using dimethylmethylene blue and hydroxyproline assays.
- Collagenase activity, MMP expression (MMP-1, MMP-3, MMP-13), and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels were assessed using bioassays, ELISA, and northern blot analysis.
- The effect of EST on MMP-1 promoter activity was evaluated using a promoter-luciferase construct.
Main Results:
- Esculetin (EST) demonstrated a dose-dependent inhibition of proteoglycan and collagen resorption in both bovine and human cartilage.
- EST significantly reduced collagenolytic activity and MMP-1 levels in stimulated cartilage cultures.
- In chondrocyte cell lines, EST suppressed the expression of MMP-1, MMP-3, and MMP-13 mRNA induced by IL1alpha + OSM, without affecting TIMP-1 levels.
- EST treatment abolished the cytokine-induced activation of the MMP-1 promoter.
Conclusions:
- Esculetin (EST) effectively inhibits the resorption of both bovine nasal and human articular cartilage.
- EST acts by downregulating the expression and activity of key matrix metalloproteinases involved in cartilage degradation.
- These findings suggest that esculetin is a potential therapeutic agent for conditions characterized by excessive cartilage breakdown.
