Bacterial wall lipopolysaccharide as a cause of intussusception in mice

Background: There is evidence that intussusception is associated with bacterial infection. It was hypothesized that a component of the bacterial wall may induce the intussusception. This study was intended to determine whether lipopolysaccharide from Escherichia coli or Salmonella can initiate intussusception in mice. Methods: Lipopolysaccharide was injected intraperitoneally in mice, and the animals were examined for the presence of intussusception from 2 to 192 hours after injection. Gastrointestinal transit was assessed by measuring the passage of charcoal in the small intestine. Transit index was defined as the ratio between the distance traveled by charcoal and the total length of the small intestine. Results: Intussusceptions were found in as much as 25.9% of lipopolysaccharide-injected animals, whereas in control animals, the incidence was zero. The threshold for the lipopolysaccharide effect was at 4 mg/kg and incidence reached a plateau at 8 mg/kg to 16 mg/kg. The incidence of intussusception peaked 6 hours after injection of lipopolysaccharide and declined to zero after 15 hours. To test the possibility that lipopolysaccharide induces intussusception by altering motility, its effect on transit index was measured. A dose of 12 mg/kg lipopolysaccharide reduced the transit index from 56.2 +/- 1.4% to 37.7 +/- 2.1% (p < 0.05). No microscopic histologic changes were found in the bowels with intussusception. Conclusions: Intraperitoneal bacterial wall lipopolysaccharide causes intussusception in mice by disturbing gastrointestinal motility.