217. Inflammatory stimulation of human decidual cells by periodontopathic bacteria

Abstract

Periodontal disease is associated with increased risk of preterm birth, although a mechanistic connection has not yet been confirmed. We hypothesised that circulating endotoxins (e.g. lipopolysaccharide, LPS) from periodontopathic organisms might possess the ability to exert highly potent immunostimulatory effects in extraplacental membranes, thereby triggering inflammatory activation sufficient to precipitate preterm labour and birth in the absence of overt intrauterine infection. We therefore tested the stimulatory effects of LPS prepared from three periodontopathic bacteria [porphyromonas gingivalis (P.g), Aggregatibacter actinomycetemcomitants (A.a), Fusobacterium nucleatum (F.n)] in comparison with ‘standard' LPS from E.Coli (O55:B5). Human decidual cells were isolated by collagenase/dispase digestion with Percoll purification from term decidual membranes delivered before the onset of labour by Caesarean section. Cells were stimulated overnight with 0.02, 0.2 and 2 mg/L LPS or equivalent doses of whole cell non-viable bacteria. As an index of inflammatory stimulation, cytokine (TNF-α) production was measured by ELISA and normalised to cellular protein. The different LPS preparations all stimulated decidual cytokine production, with ranked potencies as follows: Ec > Aa > Fn > > Pg. Maximal stimulation of TNF-α production achieved was 15-, 4.5-, 23- and 7-fold above control by Ec, Aa, Fn and Pg, respectively. Overall, the LPS preparations were more potent stimulators than whole cell bacteria, achieving greater levels of stimulation at lower doses. However, whole cell Aa was notable for its inflammatory effects, generating a >60-fold increase in TNF-α levels relative to control at the highest dose tested (2 mg/L). These data highlight wide variability in the ability of periodontopathic bacteria to stimulate an inflammatory response in the human decidua, both in terms of their potency and efficacy. The potential significance of bacterial molecular patterns other than LPS as potential triggers of inflammation-driven preterm labour warrants further investigation.