Hydrogen sulfide synergistically upregulates Porphyromonas gingivalis lipopolysaccharide-induced expression of IL-6 and IL-8 via NF-κB signalling in periodontal fibroblasts.

ABSTRACT

OBJECTIVES: The periodontal pathogen Porphyromonas gingivalis produces hydrogen sulfide (H2S). H2S in the oral cavity is positively correlated with periodontitis but the mechanism by which H2S contributes to periodontal diseases is obscure. We investigated the effect of H2S in combination with P. gingivalis lipopolysaccharide (LPS) on expression of the pro-inflammatory cytokines interleukin (IL)-6 and IL-8 in periodontal fibroblasts and the underlying mechanism of action. MATERIAL AND METHODS: Gingival fibroblasts (GFs) and periodontal ligament cells (PDLCs) were treated with different concentrations of the H2S donor NaHS in the presence/absence of P. gingivalis LPS for different time periods. Expression of IL-6 and IL-8 was detected by real-time PCR and ELISA. The activity of nuclear factor-kappa B (NF-κB) signalling was investigated using western blotting, EMSA and pathway blockade assays. RESULTS: Real-time PCR and ELISA results showed that H2S not only upregulated expression of IL-6 and IL-8 at mRNA and protein levels in a dose- and time-dependent manner, but also aggravated P. gingivalis LPS-induced expression of IL-6 and IL-8 in GFs and PDLCs. Western blotting and EMSA showed that NF-κB signalling was activated by NaHS, P. gingivalis LPS, and both, which was in accordance with the expression levels of IL-6 and IL-8 in GFs and PDLCs. These results were confirmed using a NF-κB pathway blockade assay. CONCLUSIONS: H2S synergistically upregulated P. gingivalis LPS-induced expression of IL-6 and IL-8 in GFs and PDLCs via activation of NF-κB signalling, which could promote the development of periodontitis.