Hepatic changes in mice chronically infected with Helicobacter trogontum

Abstract

We infected NIH germ-free female mice with Helicobacter trogontum, a recently described intestinal bacterium of rats, in order to study the lesions it induced in the liver of this host. Fifteen mice were challenged with a single dose of H. trogontum (test group) and killed 6, 12 and 18 months after inoculation (5 animals/group). Nine animals were challenged with 0.85% saline alone (control group) and killed at the same times. Fragments from the liver, cecum and colon were obtained for microbiologic and histologic examination. Stool samples were also collected. H. trogontum was detected in the cecum, colon and/or stool samples of all test mice. As expected, the bacterium was not isolated from any specimen obtained from the control animals. On the other hand, although we could not cultivate the bacterium from the liver, 13 test animals (86.7%) presented histological changes in this organ. The 6-month group presented infiltration of mononuclear and polymorphonuclear cells in the hepatic parenchyma and the two other groups presented foci of mononuclear cells. The results suggest that H. trogontum can elicit a hepatic inflammatory response in mice since the only difference between control and test animals was the presence of H. trogontum in the latter. This result, together with the growing number of related reports in the literature, reinforces the possible role of Helicobacter infection in the pathogenesis of hepatobiliary diseases.

Rapid Onset of Ulcerative Typhlocolitis in B6.129P2-IL10 tm1Cgn (IL-10 −/− ) Mice Infected with Helicobacter trogontum Is Associated with Decreased Colonization by Altered Schaedler's Flora

“…H. trogontum colonized the stomachs, ceca, and colons of these monoassociated mice and caused moderate, diffuse inflammation within at least one segment of the gastrointestinal tract in individual mice (30). Although H. trogontum was not recoverable from the liver, focal infiltration of inflammatory cells in the liver was suggestive of H. trogontum-associated hepatitis in monoassociated outbred NIH mice evaluated at 6, 12, and 18 months PI (32 (20,48), particularly when they are infected for a short time. We believe that the mild portal infiltrates observed in the mice euthanized at day 8 after H. trogontum infection reflected antigenic stimulation from the lower bowel via the portal circulation.…”

“…H. trogontum also has morphology and growth characteristics similar to those of, and clusters phylogenetically with, a novel intestinal helicobacter associated with ulcerative colitis in cotton-top tamarins (39) that is in taxon 10 (10). Other than in vitro studies to demonstrate expression of urease and failure to express cytolethal distending toxin (22), the potential to model human disease with H. trogontum has been evaluated only in germfree mice that developed subclinical inflammatory lesions (31,30,32).…”

Lurking in the Shadows: Emerging Rodent Infectious Diseases

“…Most disease studies have focused on H. hepaticus, but several of these other species-including H. bilis Haines et al 1998;Shomer et al 1997), H. rodentium (Maurer et al 2005;Shomer et al 1998;Whary et al 2006), H. trogontum (Moura et al 2003;Whary et al 2006), H. ganmani (Zhang et al 2005), and H. cholecystus -have been associated with a range of lesions that encompass chronic to proliferative typhlocolitis, chronic active hepatitis, and cholangiohepatitis.…”

Helicobacter pylori and Extragastric Diseases – Other Helicobacters

“…Inflammatory cells were seen in the murine hepatic parenchyma 6 months postinfection while foci of mononuclear cells were observed after longer‐term infection (> 12 months). H. trogontum was isolated from the murine colon, ceca and feces, but not from the liver [123].…”