RESUMO
@#T helper 17 (Th17) cells are a new type of CD4+ T helper cell. They participate in the immune and inflammatory response by secreting specific interleukin-17 (IL-17). In oral mucosal diseases, oral lichen planus (OLP), recurrent aphthous ulcer (RAU) and Behcet′s disease (BD) are associated with Th17 cells and IL-17. There were 17 kinds of proteins in the saliva of patients with OLP that could upregulate the expression of Th17 cells and induce the secretion of IL-17. IL-17 can stimulate epithelial cells, endothelial cells and fibroblasts to produce a variety of cytokines, such as IL-6, IL-8, granulocyte macrophage colony-stimulating factor and cell adhesion molecule-1, leading to the production and aggravation of inflammation. Th17/Tc17 cell-targeted therapy can significantly improve the clinical symptoms of OLP patients′ mucosa and skin. IL-17 can stimulate oral keratinocytes through the IL-17RA or IL-17RE receptor and produce proinflammatory effects in RAU. Th17 cells in the peripheral blood of BD patients are significantly increased, while Treg cells are significantly decreased.
RESUMO
BACKGROUND: Due to their biocompatibility and bioactivity, dicalcium silicate (C2S) and hydroxyapatite (HA) are used as coating materials for prosthetic orthopedic and dental implants or as bone substitute materials to fill bone defects. However, prostheses and bone substitutes can release particles that trigger an immune response in the recipient. The immunological effects of C2S particles have not yet been studied. OBJECTIVE: The aim of this study was to determine the cytotoxic effects of C2S particles on primary human monocytes, a human monocyte cell line (THP-1) and an osteoblast-like cell line (MG-63). The proinflammatory effects of C2S particles on THP-1 were also detected. Moreover, the osteogenic effects of C2S and HA on MG-63 cells were investigated. METHODS: Characterization of C2S and HA was performed using scanning electron microscopy (SEM), energy dispersive analysis (EDS), X-ray diffraction (XRD), Brunner-Emmett-Teller (BET) measurements and laser diffraction. The cytotoxic effect of C2S on primary human monocytes as well as THP-1 and MG-63 cells was measured using Trypan blue assays, Cell Counting Kit-8 (CCK-8) assays and flow cytometry to detect apoptosis. THP-1 human monocytes with or without lipopolysaccharide (LPS) stimulation were exposed to C2S and HA for 6 and 24h. Thereafter, the mRNA expression and protein concentrations of MMP-2, MMP-9, TIMP-2, TIMP-1 and TNF-α were evaluated using real-time PCR and ELISA, respectively. RANKL and OPG mRNA expression levels in MG-63 cells were examined using real-time PCR. RESULTS: No significant cytotoxicity was recorded when cells were directly cultured with C2S/HA particles. After THP-1 cells were cultured with C2S/HA for 24h, MMP-2, MMP-9 and TNF-α expression increased, whereas TIMP-2 and TIMP-1 expression decreased. Compared with HA, C2S slightly increased MMP-9 expression and slightly decreased TIMP-1 expression. The MMP: TIMP ratio increased in the C2S and HA groups; however, HA significantly increased the MMP-9: TIMP-1 ratio compared with C2S. Compared with HA, C2S caused less TNF-α production. C2S/HA did not modify the expression of proinflammatory mediators in LPS-stimulated cells. Furthermore, C2S/HA significantly increased OPG expression and slightly increased RANKL expression in MG-63 cells. C2S and HA decreased the RANKL: OPG ratio. CONCLUSION: Our in vitro data suggest that C2S is relatively safe when directly cultured with cells. In addition, C2S may exert proinflammatory effects; however, compared with HA, C2S had fewer proinflammatory effects on THP-1. C2S and HA did not alter the LPS-induced production of proinflammatory mediators and had similar osteogenic effects on MG-63 cells.
