Abstract
Interleukin-1β (IL-1β)-induced inflammatory response in arthritic joints include the enhanced expression and activity of matrix metalloproteinases (MMPs), and their matrix degrading activity contribute to the irreversible loss of cartilage and may also be associated with sustained chronic inflammation. We have earlier shown that green tea (Camellia sinensis) polyphenol epigallocatechin-3-gallate (EGCG) was non-toxic to human chondrocytes [Singh R, Ahmed S, Islam N, Goldberg VM, and Haqqi TM (2002) Arthritis Rheum46: 2079–2086] and inhibits the expression of inflammatory mediators in arthritic joints [Haqqi TM, Anthony DD, Gupta S, Ahmed N, Lee MS, Kumar GK, and Mukhtar H (1999) Proc Natl Acad Sci USA96: 4524–4529]. Here we show that EGCG at micromolar concentrations was highly effective in inhibiting the IL-1β-induced glycosaminoglycan (GAG) release from human cartilage explants in vitro. EGCG also inhibited the IL-1β-induced mRNA and protein expression of MMP-1 and MMP-13 in human chondrocytes. Importantly, EGCG showed a differential, dose-dependent inhibitory effect on the expression and activity of MMP-13 and MMP-1. A similar differential dose-dependent inhibition of transcription factors NF-κB and AP-1 by EGCG was also noted. These results for the first time demonstrate a differential dose-dependent effect of EGCG on the expression and activity of MMPs and on the activities of transcription factors NF-κB and AP-1 and provide insights into the molecular basis of the reported anti-inflammatory effects of EGCG. These results also suggest that EGCG or compounds derived from it may be therapeutically effective inhibitors of IL-1β-induced production of matrix-degrading enzymes in arthritis.
Footnotes
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This work was supported in part by National Institutes of Health Grants AR-44902, AR-48782, AR-07505, and AR-37726 and funds from the Department of Orthopaedics, Case Western Reserve University.
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DOI: 10.1124/jpet.103.059220.
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ABBREVIATIONS: IL, interleukin; NO, nitric oxide; MMP, metalloproteinase; MAPK, mitogen-activated protein kinase; JNK, c-Jun NH2-terminal kinase; AP-1, activating protein-1; EGCG, epigallocatechin-3-gallate; DMMB, 1,9-dimethylmethylene blue; DMEM, Dulbecco's modified Eagle's medium; ELISA, enzyme-linked immunosorbent assay; RT-PCR, reverse transcription-polymerase chain reaction; TAMRA, 5-carboxytetramethylrhodamine; FAM, 5-carbofluorescein; NF-κB, nuclear factor-κB; RLU, relative light units; TIMP-1, tissue inhibitor of metalloproteinase 1; GAG, glycosaminoglycan; ANOVA, analysis of variance; ROS, reactive oxygen species; PAGE, polyacrylamide gel electrophoresis; SEAP, secreted alkaline phosphatase; OA, osteoarthritis.
- Received August 27, 2003.
- Accepted October 31, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
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