Hydrogen Sulfide Modulates Interleukin-8 Transcript Stability in Periodontal Ligament Fibroblast

Objective: Hydrogen sulfide (H₂S), a metabolic byproduct of periodontal anaerobes, is a major contributor of halitosis. It has recently been recognized as a gaseous mediator with physiologically diverse functions, including modulation of inflammation. Human periodontal ligament fibroblast (PDLF) expresses various pattern recognition receptors involved in sensing and initiation of innate immune response against bacterial infection. While high concentrations of H₂S have been reported in periodontal pockets of patients, its potential role in modulating immune responses in PDLF has not been explored. Since interleukin-8 (IL-8) is a key chemo-attractant of neutrophils during periodontitis, the objective of this study was to determine if H₂S modulates IL-8 production in PDLF. Methods: qPCR and ELISA were carried out to quantify the production of IL-8 mRNA and protein respectively in PDLFs treated with the H₂S donor, sodium hydrosulfide (NaHS). To determine if H₂S-mediated IL-8 production was mediated by either p38 MAPK or NFκB pathways, cells were treated with SB203580 and BAY11-7082 respectively. ActinomycinD chase experiment was performed to determine if H₂S treatment affected the stability of IL-8 transcript. The effect of NaHS on cell viability was determined by MTS assay. Results: H₂S did not significantly affect viability of PDLF. Exposure to H₂S led to significant increase in IL-8 production in a dose-dependent manner. Disruption of p38 MAPK and not NFκB signaling pathway resulted in a significant decrease in H₂S-mediated IL-8 production. Increased H₂S-mediated IL-8 level was found to be modulated at level of mRNA stability. Conclusion: IL-8 is a key cytokine involved in the initiation and progression of periodontitis. We show for the first time that H₂S modulates IL-8 production in PDLFs through p38 MAPK-dependent enhancement of transcript stability. This study thus provides evidence for a possible contributory role of H₂S to periodontal inflammation.

This study was supported by R221-000-054-101 from Faculty of Dentistry, NUS.