Deciphering the Chemical Lexicon of Host–Gut Microbiota Interactions

The human intestine harbors an immense, diverse, and critical population of bacteria that has effects on numerous aspects of host physiology, immunity, and disease. Emerging evidence suggests that many of the interactions between the host and the gut microbiota are mediated via the microbial metabolome, or the collection of small-molecule metabolites produced by intestinal bacteria. This review summarizes findings from recent work by focusing on different classes of metabolites produced by the gut microbiota and their effects in modulating host health and disease. These metabolites ultimately serve as a form of communication between the gut microbiome and the host, and a better understanding of this chemical language could potentially lead to novel strategies for treating a wide variety of human disorders. Microbially produced metabolites serve as chemical signals between the gut microbiota and the host and regulate many tissues throughout the body, thereby influencing host physiology.Gut microbiota metabolites modulate host immune responses and inflammation, thereby influencing host health and disease.Disorders affected by gut microbial metabolites include metabolic syndrome, inflammatory bowel diseases, cancer, allergy, autoimmune diseases, and neurodegenerative diseases.The gut microbial metabolome can modulate colonization resistance against intestinal infections due to direct inhibition of enteric pathogens or by improving host defense mechanisms.Identifying the molecular mechanisms that influence these outcomes is critical to understanding the impact of the gut microbiome and their metabolites on the host.Understanding the individual and systemic effects of these metabolites is important for deciphering the chemical lexicon of the gut microbiota.