Researchers have used a mouse model to show that infections in the intestine can change the composition of bile, a fluid that is generated in the liver and is crucial to digestion. Bile aids in the absorption of fat and contributes to defense against infections. This study has suggested that intestinal infections can alter microbes in the gastrointestinal tract, or the microbiome, and modify the immune system. Although the work was conducted in mice, the researchers suggested that their conclusions also apply to humans. The findings have been reported in Nature Microbiology.
"The changes we detected in the composition of bile with infection are beneficial for the intestine to clear infection," said corresponding study author Matthew Waldor, MD, PhD, of Brigham and Women's Hospital. "Our findings reveal the intricate and dynamic nature of bile composition, shedding new light on the liver's critical role in defending the intestine from infection. These insights enhance our understanding of the liver's broader functions in regulating physiological stability and metabolic processes."
Although scientists have investigated bile and know a lot about it, the composition of bile has not been studied in many different contexts. In this study, the researchers suspected that infections may shift bile function and composition. With a mouse model, the researchers assessed how infections with one of two bacterial pathogens impacted bile. One pathogenic bacterium was C. rodentium, which infects the mouse cecum and colon, and L. monocytogenes, which infects the mouse intestine, gall bladder, and liver.
Both bacterial infections caused specific changes in metabolic compounds that are present in bile. The researchers identified hundreds of metabolites in the bile metabolome, and many changes that happen during a gut infection. These changes likely boost host defense against infection.
While this research has provided many new insights into how intestinal infections can affect the composition of bile, the 812 metabolites highlighted in this study are also probably only some of the metabolites that may be found in bile, the study authors noted. More of these metabolites will likely be revealed with additional studies that use advanced mass spectrometry tools that are not yet available.
