RESUMO
OBJECTIVES: The first objective of the present study was to investigate TNF-ð¼ secretion by macrophages stimulated with endodontic pathogens and bacterial cell surface components. The second objective was to assess the in vitro effects of TNF-ð¼ on periostin, cytokine, and matrix metalloproteinase (MMP) secretion by and the viability, proliferation rate, and mineralization potential of stem cells of the apical papilla (SCAP). METHODS: TNF-ð¼ secretion by macrophages stimulated with either endodontic pathogens or bacterial surface components was assessed using an enzyme-linked immunosorbent assay (ELISA). The viability and proliferation rate of SCAP treated with TNF-ð¼ were assessed using a colorimetric MTT assay. The mineralization potential of TNF-ð¼-treated SCAP was determined by Alizarin Red staining. Periostin secretion by SCAP was determined by ELISA while cytokine and MMP secretion were assessed using a multiplexing laser bead assay. RESULTS: TNF-ð¼ secretion by macrophages increased following a stimulation with Gram-negative and Gram-positive endodontic pathogens. Lipopolysaccharide and lipoteichoic acid also dose-dependently increased the secretion of TNF-ð¼ by macrophages. The viability, proliferation rate, and mineralization activity of SCAP were negatively affected by a TNF-ð¼ treatment. Treating SCAP with TNF-ð¼ attenuated the secretion of periostin and upregulated the secretion of several cytokines and MMPs. CONCLUSIONS: TNF-ð¼ exerts deleterious effects on SCAP by affecting their viability, proliferation rate, and mineralization potential. By its ability to induce the secretion of pro-inflammatory cytokines and MMPs by SCAP, TNF-ð¼ can contribute to creating an inflammatory environment, promoting tissue destruction, and consequently interfering with the success of regenerative endodontic therapy. CLINICAL RELEVANCE: TNF-ð¼ has deleterious impacts on stem cells of the apical papilla and may compromise the outcome of regenerative endodontic therapy.