Pathogenicity of Serpulina hyodysenteriae: in vivo induction of tumor necrosis factor and interleukin-6 by a serpulinal butanol/water extract (endotoxin).

Lipopolysaccharide (LPS) of Gram-negative bacteria is a classic inducer of inflammatory cytokines. In the present experiments, LPS-like (phenol/water extract) or endotoxin-like (butanol/water extract) preparations from Serpulina hyodysenteriae were examined for their ability to induce serum tumor necrosis factor (TNF) or interleukin (IL)-6 bioactivity in mice and swine. Serpulina hyodysenteriae endotoxin (butanol/water extract) elicited increased serum TNF activity in mice, although serpulinal endotoxin was at least 10 times less potent than the LPS preparations of E. coli or S. typhimurium on a weight basis for induction of TNF bioactivity. S. hyodysenteriae LPS induced lower levels of serum TNF in mice than S. hyodysenteriae endotoxin. In contrast, pigs injected with S. hyodysenteriae endotoxin demonstrated no increase in serum TNF activity. However, an induction of IL-6 bioactivity was observed in serum samples from pigs injected with serpulinal endotoxin. In pigs, the serpulinal preparations were five times less potent (on a weight basis) than E. coli or S. typhimurium LPS for induction of IL-6 bioactivity. These data indicate that serpulinal endotoxin, although less bioactive than E. coli or S. typhimurium LPS, is nonetheless capable of inducing the in vivo production of specific pro-inflammatory cytokines.