Citrobacter rodentium induced liver changes in C57BL/6 mice : animal model of acute inflammatory stress and injury

Abstract

The activation of inflammatory responses, while critical for host defense, contributes to hepatic injury in numerous acute and chronic liver disease states as well as drug-induced liver injury (DILI). The interactions that mediate susceptibility to liver injury and disease, however, are still poorly understood, underscored by the complexity of immune interactions and the diverse cellular composition and functions of the liver. Using Citrobacter rodentium, a well characterized rodent-specific enteric pathogen as a source of extrahepatic inflammatory stress; host liver responses, metabolic dysregulation, and susceptibility to injury in C57BL/6 mice were investigated. For the first time, we show altered liver pathology during the early course of C. rodentium infection, characterized by periportal necrosis indicative of thrombic ischemic injury, correlating with distinct circulating and tissue specific cytokine/chemokine profiles. Using Acetaminophen (APAP), a widely used analgesic and well-characterized hepatotoxin, we evaluated liver responses in isolation and in the context of host inflammation to gain insight into the role of live bacterial infection in altering liver metabolism and susceptibility to DILI. We combined systemic and tissue-specific cytokine/chemokine levels, clinical serum chemistries, and histopathological assessments of hepatic and enteric inflammation and necrosis to measure molecularlevel responses to treatment and their physiological effect. Using principal components analysis (PCA), clustering, partial least squares regression (PLSR), and a combination mutual-information-correlation network, enabled detection and visualization of both linear and nonlinear dependencies between molecules and physiological states across tissues and timepoints. C. rodentium-induced inflammatory stress was finally investigated for its potential in altering drug pharmacokinetics (PK) of substrates varying in their metabolic biotransformation and clearance mechanisms. Infection resulted in increased systemic oral exposure (AUC) of clinically relevant xenobiotics such as verapamil, propranolol, and digoxin. Functionally, these changes were not found dependent on CYP-mediated biotransformation of parent compounds; rather, they appear driven more by proposed gut barrier compromise. In conclusion, gastrointestinal infection with C. rodentium alters systemic and hepatocytes specific responses, not previously appreciated from this enteric pathogen, making it a useful model for studying host-pathogen interactions under acute hepatic inflammatory stress and injury.