EGCG, a bioactive phytochemical found in green tea, was found to regulate transforming growth factor β-activated kinase 1 (TAK1) in human rheumatoid arthritis synovial fibroblasts (RASF), indicating that TAK1 regulation may be a therapeutic target in RA. EGCG appears to effectively inhibit TAK1 by blocking its phosphorylation. As a mediator of inflammation, TAK1 is integral to the activation of downstream mitogen-activated protein kinases (MAKPs) in response to receptor stimulation by the inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor (TNF). A team of researchers led by Associate Professor Salah-uddin Ahmed of Washington State University College of Pharmacy in Spokane, analyzed the mechanism of TAK1 regulation in a pre-clinical mouse model of human RA. After 10 days of treatment with EGCG, the researchers found a significant reduction in ankle circumference, a measurement used as a surrogate for symptomatic inflammation. Authors stated that they have provided a rationale for targeting RASF TAK1 in RA and identified a unique mechanism through which EGCG inhibits the interaction between signaling molecules important in cytokine signaling, ultimately inhibiting inflammation and tissue destruction in RA.
Singh AK, Umar S, Riegsecker S, et al Regulation of transforming growth factor β-activated kinase activation by epigallocatechin-3-gallate in rheumatoid arthritis synovial fibroblasts: suppression of K63-linked autoubiquitination of tumor necrosis factor receptor-associated factor 6. Arthritis Rheum. 2016;68(2):347-358.
CP Sison (Med Editor) Rheumatoid Arthritis Advisor. March 01, 2016