BACKGROUND: Acute liver injury is a common clinical disorder associated with intestinal barrier injury and disturbance of intestinal microbiota. Probiotic supplementation has been reported to reduce liver injury; however, it is unclear whether enteropathogen infection exacerbates liver injury. The purpose of this study was to address this unanswered question using a rat model.
METHODS: Oral supplementation with Salmonella enterica serovar enteritidis (S. enteritidis) was given to rats for 7 days. Different degrees of acute liver injury were then induced by intraperitoneal injection of D-galactosamine. The presence and extent of liver injury was assayed by measuring the concentrations of serum alanine aminotransferase, aspartate aminotransferase, and total bilirubin. Histology was used to observe liver tissue damage. Additionally, we measured the changes in plasma endotoxin, serum cytokines and bacterial translocation to clarify the mechanisms underlying intestinal microbiota associated liver injury.
RESULTS: The levels of liver damage and endotoxin were significantly increased in the Salmonella infected rats with severe liver injury compared with the no infection rats  with severe liver injury (P<0.01); The peyer’s patch CD3+ T cell counts were increased significantly when the Salmonella infection with severe injury group was compared with the normal group (P<0.05). S. enteritidis pretreatment enhanced intestinal barrier impairment and bacterial translocation.
CONCLUSIONS: Oral S. enteritidis administration exacerbates acute liver injury, especially when injury was severe. Major factors of the exacerbation include inflammatory and oxidative stress injuries induced by the translocated bacteria and associated endotoxins, as well as over-activation of the immune system in the intestine and liver.