Abstract
IL‐6 is well recognized to be a potent bone resorptive agent and thus in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins in green tea, and theaflavin‐3,3′‐digallate (TFDG), polyphenol in black tea, have multiple beneficial effects, but the effects of catechins and theaflavins on IL‐6 production in human gingival fibroblasts (HGFs) are not known. In this study, we investigated the mechanisms by which EGCG, ECG, and TFDG inhibit tumor necrosis factor superfamily 14 (TNFSF14)‐induced IL‐6 production in HGFs. We detected TNFSF14 mRNA expression in human diseased periodontal tissues. TNFSF14 increased IL‐6 production in HGFs in a concentration‐dependent manner. EGCG, ECG, and TFDG prevented TNFSF14‐mediated IL‐6 production in HGFs. EGCG, ECG, and TFDG prevented TNFSF14‐induced extracellular signal‐regulated kinase (ERK), c‐Jun N‐terminal kinase (JNK), and nuclear factor‐κB activation in HGFs. Inhibitors of ERK, JNK, and nuclear factor‐κB decreased TNFSF14‐induced IL‐6 production. In addition, EGCG, ECG, and TFDG attenuated TNFSF14 receptor expression on HGFs. These data provide a novel mechanism through which the green tea and black tea polyphenols could be used to provide direct benefits in periodontal disease.