A Modular Liver-Microbial Microfluidic Platform to Evaluate Therapeutic and Adverse Effects of Microbial Metabolites.

Gut microbial metabolites, particularly short-chain fatty acids (SCFAs) like butyrate, play a significant role in modulating non-alcoholic fatty liver disease (NAFLD). While animal studies show that butyrate-producing microbes can improve liver function, full recovery is hindered by unintended side effects from commensal bacteria. These underlying biomolecular mechanisms remain elusive, due to the lack of in vitro coculture models capable of systematically examine both the therapeutic benefits of engineered microbial metabolites and their potential adverse impacts. To address this, we developed a modular microfluidic platform to study the effects of live microbial metabolites on hepatic steatosis and liver function. We created a microfluidic-based hepatic steatosis model integrated with a compartmentalized microbial module, facilitating the study of how metabolites produced by live microbes affected the liver model. We compared the effects of synthetic SCFA supplementation with those of coculturing with a control and butyrate-producing E. coli Nissle 1917 (EcN) strains on hepatic steatosis. Our findings showed that live microbial coculture did not phenocopy exogenous SCFA treatment. While both treatments reduced steatotic lipid accumulation, live microbes induced inflammatory and hepatic metabolic changes, suggesting contributions from additional microbial factors, emphasizing the need to thoroughly assess side effects in liver disease treatment.