IL-6 Production In Human Gingival Fibroblasts Research Articles

Biological effects of interleukin‐6 on Gingival Fibroblasts: Cytokine regulation in periodontitis

Periodontitis is a bacterial infectious disease, and many inflammatory cytokines regulate periodontitis pathophysiology through a crosstalk between tissue cells and immune cells. Interleukin (IL)-6 is an important cytokine involved in the regulation of host response to bacterial infection. Human Gingival Fibroblasts (HGFs) are the most abundant cells in gingival connective tissues. Various HGF responses to periodontal pathogens or inflammatory cytokines contribute to the development of periodontitis. Lipopolysaccharide derived from Porphyromonas gingivalis (Pg LPS) and IL-1β significantly increase IL-6 production in HGFs. However, IL-6 cannot function in HGFs without the soluble form of the IL-6 receptor (sIL-6R), because HGFs do not express sufficient cell surface IL-6R to bind appreciable levels of IL-6. Importantly, sIL-6R is essential for IL-6 signaling in HGFs, and the sIL-6R is produced by differentiated THP-1 cells treated with IL-6. Calprotectin, a heterodimer of S100A8 and S100A9, is released during inflammation and significantly induces IL-6 production in HGFs via toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signals. Calprotectin also induces sIL-6R production in differentiated THP-1 cells. IL-6 induces vascular endothelial growth factor (VEGF), matrix-metalloproteinase-1 (MMP-1), and cathepsin L production in HGFs in the presence of sIL-6R. Taken together, calprotectin-induced IL-6 production in HGFs may cause periodontitis progression through a crosstalk of fibroblasts and macrophages. There are many reports that examine how cytokines are released from HGFs to cause beneficial or harmful effects in inflamed periodontal lesions. This review explores the pathophysiology of periodontitis by focusing IL-6-mediated crosstalk of HGFs and macrophages.

Tea polyphenols inhibit IL‐6 production in tumor necrosis factor superfamily 14‐stimulated human gingival fibroblasts

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-kappaB activation in HGFs. Inhibitors of ERK, JNK, and nuclear factor-kappaB 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.