N-acetyl cysteine inhibits lipopolysaccharide-mediated synthesis of interleukin-1β and tumor necrosis factor-α in human periodontal ligament fibroblast cells through nuclear factor-kappa B signaling

Background: The aim of this study was to investigate the role of n-acetyl cysteine (NAC) in the lipopolysaccharide (LPS)-mediated induction of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) synthesis by human periodontal ligament fibroblast cells (hPDLFs). In addition, we aimed to determine the involvement of the nuclear factor-kappa B (NF-kappa B) pathway in any changes in IL-1 beta and TNF-alpha expression observed in response to LPS and NAC. Methods: HPDLFs were obtained by primary culture. The culture medium used in this experiment was Dulbecco's Modified Eagle Medium (DMEM low-glucose). Cells were stimulated with various concentrations of NAC or LPS. Cell proliferation was measured at various time-points with the cell Counting Kit 8 (CCK-8) assay. mRNA levels of IL-1 beta and TNF-alpha were determined by real-time quantitative polymerase chain reaction (RT-qPCR) analysis. Protein levels of IL-1 beta and TNF-alpha were measured by enzyme-linked immunosorbent assay (ELISA). Protein and mRNA expression levels of NF-kappa B were measured by western blot and RT-qPCR. Results: The results showed that LPS treatment in hPDLFs induced mRNA and protein expression of IL-1 beta TNF-alpha, and NF-kappa B. However, these effects were eliminated by pretreatment with NAC. Pretreatment with both NAC (1 mmol/L) and BAY11-7082 (10mmol/L) significantly inhibited the NF-kappa B activity induced by LPS. Conclusion: NAC inhibits the LPS-mediated synthesis of tumor TNF-alpha and IL-1 beta in hPDLFs, through the NF-kappa B pathway.