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New Insights into Bile Composition and its Role in Fighting Intestinal Infections

Intestinal infections can alter the composition of liver bile, impacting immune function and gut microbiota, which may enhance the body’s ability to combat harmful bacteria.

Recent research from Brigham and Women’s Hospital has unveiled a significant axis of host defense linked to enteric infections, a term broadly encompassing various intestinal ailments, including the common “stomach flu.” The study investigates the pivotal role of bile—a digestive fluid produced by the liver known for its function in fat absorption—in the body’s response to infections. Although the investigation utilized a mouse model, the researchers believe the implications of their findings extend to human biology as well. The results of this study have been published in the journal Nature Microbiology.

According to Matthew Waldor, MD, PhD, from the Brigham’s Division of Infectious Diseases, “The compositional changes we observed in bile during infection serve to aid the intestine in combatting these infections. Our insights illustrate the complex and adaptable nature of bile composition, highlighting the liver’s essential role in protecting the intestine against infections. These findings also provide a deeper understanding of how the liver contributes to overall physiological balance and metabolism.”

Traditionally, studies on bile have primarily concentrated on its role in nutrient absorption, with less emphasis on its compositional attributes, especially during enteric infections. The researchers posited that infections would prompt a shift in bile composition, given its critical role in mediating communication between the liver and gut.

Utilizing a detailed metabolic analysis in a mouse model, this research examined the alterations in bile metabolites following an enteric infection. The subjects were infected with either L. monocytogenes, which proliferates in the intestine, liver, and gallbladder, or C. rodentium, which primarily affects the caecum and colon. The study revealed that different pathogens produced both distinct and overlapping changes in bile metabolite profiles. Notably, the researchers identified hundreds of new metabolites within the bile metabolome. More critically, the study demonstrated that enteric infections lead to dynamic alterations in bile composition, enhancing intestinal defenses. Although the identification of 812 bile metabolites marks a significant advancement in understanding bile composition, the researchers caution that this number likely represents only a fraction of the total bile metabolites, suggesting that further discoveries are on the horizon as techniques in tandem mass spectrometry advance.

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