Epigallocatechin-3-gallate ameliorates both obesity and autoinflammatory arthritis aggravated by obesity by altering the balance among CD4+ T-cell subsets

Epigallocatechin-3-gallate (EGCG) is the most biologically active catechin in green tea. EGCG has been shown to have therapeutic effects in autoinflammatory diseases and obesity. Obesity is currently regarded partly as an inflammatory condition because of the inflammatory cytokines and higher Th1 cell differentiation detected in obese animal models and human cohort studies. In this work, the effects of EGCG on diet-induced obesity (DIO) mice and obese collagen-induced arthritis (CIA) mice were investigated. EGCG reduced the body weight and fat infiltration in liver tissue while improving serum lipid profiles in DIO mice. EGCG also induced a higher Treg/Th17 cell ratio in CD4(+) T-cell differentiation by decreasing the ratio of STAT3/STAT5 expression in DIO mice. EGCG was also effective in obese CIA mice. Reducing Th17 cells and increasing regulatory T (Treg) cells by affecting the STAT protein ratio were important effects of EGCG that might result in improved arthritic scores and levels of several inflammatory indicators. Thus, EGCG has an anti-inflammatory effect by suppressing STAT3 proteins and Th17-cell differentiation. EGCG thus shows promise for treating autoimmune conditions related to STAT3 or Th17 cells, such as metabolic syndrome, inflammatory arthritis, and some neoplastic diseases. (C) 2013 Elsevier B.V. All rights reserved.