Action of bacterial extracts from Aggregatibacter actinomycetemcomitans in the production of IL-6 and IL-8 by human gingival fibroblasts

Abstract number: P730

Gonzalez O., Roa N., Valdivieso C., Gamboa F.

Objective: Periodontal disease is refers to a pathological response that cause inflammation and loss of supporting structures of the teeth. Aggregatibacter actinomycetemcomitans is a Gram-negative bacillus associated to aggressive forms of periodontitis. This microorganism express a cytolethal distending toxin (Cdt), which induces cell cycle arrest and modulates cytokine synthesis. The aim of this study was to evaluate the action of two bacterial extracts from A. actino­mycetem­comitans (Cdt mutant and wild-type strains) in the production of IL-6 and IL-8 by human gingival fibroblasts (HGF).

Methods: The supernatants from HGF primary cell cultures were exposed to either wild type A. actino­mycetem­comitans or Cdt mutant strain bacterial extracts. The IL-6 and IL-8 production was determined by using a cytometric bead array human inflammation kit (Becton-Dickinson).

Results: There were not significant differences in IL-6 and IL-8 levels produced by HGF challenged with wild type or Cdt mutant bacterial extracts. However, when response to lipopolysaccharide was not controlled by preincubation of HGF with antibodies anti-CD14 and anti-TLR4 before bacterial challenge, IL-8 production was significantly reduced in HGF stimulated with Cdt mutant but not with A. actino­mycetem­comitans wild type strain.

Conclusion: These results suggest that Cdt does no affect directly the IL-6 and IL-8 production by HGF in vitro. Nevertheless, a potential indirect immunostimulatory role of Cdt in HGF may be associated with other A. actino­mycetem­comitans bacterial components such as lipopolysaccharide, which has to be studied.