Hemorrhage-induced intestinal damage is complement independent in Helicobacter hepaticus infected mice

Abstract

With over half of the world population infected, Helicobacter infection is an important public health issue associated with gastrointestinal cancers and inflammatory bowel disease. Animal studies indicate that complement and oxidative stress play a role in Helicobacter infections. Hemorrhage induces tissue damage which is attenuated by blockade of either complement activation or oxidative stress products. Therefore, we hypothesized that chronic Helicobacter hepaticus infection would modulate hemorrhage-induced intestinal damage and inflammation. To test this hypothesis, we examined hemorrhage-induced jejunal damage and inflammation in uninfected and H. hepaticus infected mice. H. hepaticus infection increased hemorrhage-induced mid-jejunal mucosal damage despite attenuating complement activation. In addition, infection alone increased chemokine secretion, changing the hemorrhage-induced neutrophil infiltration to a macrophage-mediated inflammatory response. The hemorrhage-induced macrophage infiltration correlated with increased secretion of tumor necrosis factor-α (TNF-α³) and nitric oxide (NO) in the infected mice. Together these data indicate that Helicobacter infection modulates the mechanism of hemorrhage-induced intestinal damage and inflammation from a complement-mediated response to a macrophage response with elevated TNF-α and NO. These data indicate that chronic, low level infections change the response to trauma and should be considered when designing and administering therapeutics.