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Open Access Highly Accessed Research article

Green tea polyphenol epigallocatechin-3-gallate inhibits advanced glycation end product-induced expression of tumor necrosis factor-α and matrix metalloproteinase-13 in human chondrocytes

Zafar Rasheed1, Arivarasu N Anbazhagan1, Nahid Akhtar1, Sangeetha Ramamurthy1, Frank R Voss2 and Tariq M Haqqi1*

Author affiliations

1 Department of Pathology, Microbiology, & Immunology, School of Medicine, University of South Carolina, 6439 Garners Ferry Rd, Columbia, SC 29209, USA

2 Department of Orthopaedics, University of South Carolina, School of Medicine/Palmetto Richland Hospital, Two Medical Park, Columbia, SC 29203, USA

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Citation and License

Arthritis Research & Therapy 2009, 11:R71  doi:10.1186/ar2700

Published: 15 May 2009

Abstract

Introduction

The major risk factor for osteoarthritis (OA) is aging, but the mechanisms underlying this risk are only partly understood. Age-related accumulation of advanced glycation end products (AGEs) can activate chondrocytes and induce the production of proinflammatory cytokines and matrix metalloproteinases (MMPs). In the present study, we examined the effect of epigallocatechin-3-gallate (EGCG) on AGE-modified-BSA (AGE-BSA)-induced activation and production of TNFα and MMP-13 in human OA chondrocytes.

Methods

Human chondrocytes were derived from OA cartilage by enzymatic digestion and stimulated with in vitro-generated AGE-BSA. Gene expression of TNFα and MMP-13 was measured by quantitative RT-PCR. TNFα protein in culture medium was determined using cytokine-specific ELISA. Western immunoblotting was used to analyze the MMP-13 production in the culture medium, phosphorylation of mitogen-activated protein kinases (MAPKs), and the activation of NF-κB. DNA binding activity of NF-κB p65 was determined using a highly sensitive and specific ELISA. IκB kinase (IKK) activity was determined using an in vitro kinase activity assay. MMP-13 activity in the culture medium was assayed by gelatin zymography.

Results

EGCG significantly decreased AGE-stimulated gene expression and production of TNFα and MMP-13 in human chondrocytes. The inhibitory effect of EGCG on the AGE-BSA-induced expression of TNFα and MMP-13 was mediated at least in part via suppression of p38-MAPK and JNK activation. In addition, EGCG inhibited the phosphorylating activity of IKKβ kinase in an in vitro activity assay and EGCG inhibited the AGE-mediated activation and DNA binding activity of NF-κB by suppressing the degradation of its inhibitory protein IκBα in the cytoplasm.

Conclusions

These novel pharmacological actions of EGCG on AGE-BSA-stimulated human OA chondrocytes provide new suggestions that EGCG or EGCG-derived compounds may inhibit cartilage degradation by suppressing AGE-mediated activation and the catabolic response in human chondrocytes.