Green tea polyphenol epigallocatechin 3-gallate in arthritis: progress and promise

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by the activation of synovial tissue lining the joint capsule, which results in the invasion of the cartilage and bone leading to the progressive joint dysfunction [1]. Severe morbidity and structural damage of joints caused by chronic inflammation often lead to major personal, family, and financial consequences, as well as increased mortality. Recent understanding of the RA pathogenesis has clarified the role of cytokines and other inflammatory mediators in this process and has provided a scientific rationale in the process of developing targeted therapies [2].Osteoarthritis (OA) is a common disorder of synovial joints characterized pathologically by focal areas of damage to the articular cartilage, centered on load-bearing areas, which is associated with new bone formation at the joint margins (osteophytosis), changes in the subchondral bone, variable degrees of mild synovitis, and thickening of the joint capsule [3]. The severity of OA differs from patient to patient, but the very common clinical symptoms include pain, reduced range of motion, inflammation, and deformity [4]. This condition is strongly age related, being less common before the age of 40 but showing a marked increase in frequency with age [3]. Although OA is considered the disease of the destruction of articular cartilage, recent evidence suggests that it may also damage bone and synovium in the arthritic joints [3,4]. Despite existing evidence of the crosstalk between tissues at the cellular and molecular levels, however, intertwined pathophysiological processes causing OA have reduced the focus in choosing from one of these three tissues - articular cartilage, bone, or synovium - to serve as the key therapeutic target [3].Conventional disease-modifying anti-rheumatic drugs such as methotrexate have long been the mainstay of RA treatment and are still advocated as a first-line option in newly diagnosed RA patients [5]. Whil