Calprotectin Induces IL‐6 and MCP‐1 Production via Toll‐Like Receptor 4 Signaling in Human Gingival Fibroblasts

Abstract

Calprotectin, a heterodimer of S100A8 and S100A9 molecules, is associated with inflammatory diseases such as inflammatory bowel disease. We have reported that calprotectin levels in gingival crevicular fluids of periodontitis patients are significantly higher than in healthy subjects. However, the functions of calprotectin in pathophysiology of periodontitis are still unknown. The aim of this study is to investigate the effects of calprotectin on the productivity of inflammatory cytokines in human gingival fibroblasts (HGFs). The HGFs cell line CRL-2014® (ATCC) were cultured, and total RNAs were collected to examine the expression of TLR2/4 and RAGE mRNA using RT-PCR. After the cells were treated with S100A8, S100A9, and calprotectin, supernatants were collected and the levels of IL-6 and MCP-1 were measured using ELISA methods. To examine the intracellular signals involved in calprotectin-induced cytokine production, several chemical inhibitors were used. Furthermore, after the siRNA-mediated TLR4 down-regulated cells were treated with S100A8, S100A9, and calprotectin, the levels of IL-6 and MCP-1 were also measured. HGFs showed greater expression of TLR4 mRNA, but not TLR2 and RAGE mRNA compared with human oral epithelial cells. Calprotectin increased significantly the production of MCP-1 and IL-6 in HGFs, and the cytokine productions were significantly suppressed in the cells treated with MAPKs, NF-κB, and TLR4 inhibitors. Furthermore, calprotectin-mediated MCP-1 and IL-6 production were significantly suppressed in TLR4 down-regulated cells. Taken together, calprotectin induces IL-6 and MCP-1 production in HGFs via TLR4 signaling that involves MAPK and NF-κB, resulting in the progression of periodontitis. J. Cell. Physiol. 232: 1862-1871, 2017. © 2016 Wiley Periodicals, Inc.

Neutrophil calprotectin identifies severe pulmonary disease in COVID-19

“…(29) and ultimately trigger the production of pro-inflammatory cytokines (30). Depending on the system, calprotectin has been detected both upstream (31) and downstream (32) of IL-6, which has emerged as a possible therapeutic target in COVID-19. Calprotectin is also a potent stimulator of neutrophils themselves, promoting degranulation and phagocytosis (33,34), as well as other more recently described effector functions such as neutrophil extracellular trap (NET) release (35).…”

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

“…Narumi et al () reported that natural killer (NK) cells are activated via calprotectin‐RAGE signaling, and calprotectin‐induced NK cell activation may be useful for cancer immunotherapy. Importantly, human oral epithelial cells constitutively express both TLR4 mRNA and RAGE mRNA, whereas HGFs express TLR4 mRNA constitutively, but not RAGE mRNA (Nishikawa et al, ). These results indicate that TLR4 may be the main target receptor for calprotectin in HGFs.…”

High Glucose-Mediated Cytokine Regulation in Gingival Fibroblasts and THP-1 Macrophage: a Possible Mechanism of Severe Periodontitis with Diabetes

“…In addition, significant elevation of calprotectin (CPT), a heterodimer of S100A8 and S100A9, are found in inflamed periodontal tissues [7]. Our previous findings showed that CPT induces not only IL-6 production in HGFs [12], but also sIL-6R production in THP-1 macrophages [7], resulting in progression of periodontitis by induction of IL-6 cascades. Furthermore, vascular endotherial growth factor (VEGF) is a significant factor for diabetic complications, and is implicated in the development of neovascularization and endotherial dysfunction in diabetic retinopathy [13].…”