(775e) A Novel Integrated Intestine-Liver-Brain Model to Investigate Ethanol Metabolism 

To date, in vitro models of the gastrointestinal (GI) tract and liver have been developed separately with very limited efforts to integrate them into a single system. The communications between the GI and liver modulate multiple metabolic functions, inflammatory responses and the biotransformation of chemicals. Ethanol-induced toxicity can have severe consequences on all three of these organs. In the liver, excessive ethanol consumption can lead to fibrosis, while significant cell death has been reported in intestines exposed to ethanol. Excessive alcohol consumption can be toxic to neurons in the brain. There is a need to understand how these organs function cohesively to metabolize ethanol. More importantly, the effects of the metabolites secreted by these organs on the brain are not fully understood.

We describe a novel integrated GI-liver model that is designed by integrating a primary rat ileum explant with a 3D organotypic multi-cellular liver model. Primary ileum tissues were surgically excised from rats. These explants were cultured in oxygenated culture medium that contained antibiotics. The ileum cultures remained stable with virtually no shedding of the intestinal epithelium. Ethanol (EtOH) was administered over 100-1000mM concentration range. These concentrations ranged from sub-lethal to highly toxic. Upon exposing the integrated ileum-liver cultures to 100mM EtOH for 24 hours, significant changes in hepatic function were observed. Albumin levels were approximately 2-fold lower in the integrated ileum-liver models when compared to liver models. A similar trend was also observed in urea production. The integrated ileum-liver models exhibited significantly lower urea levels compared to liver models alone.

EtOH administration is known to result in cell death and in the production of reactive oxygen species (ROS). Hepatocytes in the integrated cultures and liver models were imaged for ROS production upon EtOH administration. Even at a sub-lethal dose of 100mM EtOH, ROS production was significantly higher in the integrated cultures when compared to cells in the liver models alone. Interestingly, ROS production by the integrated ileum-liver culture was higher than liver models that had been treated with a combination of LPS (lipopolysaccharide) and 100mM EtOH.

Astrocyte cultures were exposed to EtOH in culture medium or spent medium obtained from the integrated ileum-liver models. The viabilities of astrocytes exposed to condition medium obtained from EtOH treated gut-liver models were approximately 2-fold lower compared to cultures that were exposed only to EtOH. These trends clearly demonstrate that the integrated gut-liver models exhibit increased sensitivity to EtOH.

Ongoing efforts are focused upon measuring the levels of inflammatory cytokines and production of reactive oxygen species when this multi-organ model (gut-liver-brain) is treated with EtOH. Integrating the GI, liver and brain will serve as a powerful platform to provide holistic information on toxicity, inflammatory response and organ crosstalk.