L-serine at the crossroads of microbiota, intestinal health, and disorders.

L-serine is an amino acid involved in maintaining intestinal mucosal homeostasis through its role in protein synthesis but also in redox balance, immune function and lipid metabolism. It also contributes to mucus production, the epithelial barrier integrity and gut microbiota composition. Prokaryotic cells, including Escherichia coli, have developed mechanisms to exploit L-serine to support their growth, virulence, inflammatory and/or carcinogenic properties. In this review, we summarize current findings on L-serine metabolism in the intestinal mucosal homeostasis, its interactions with microbiota, and its modulation in digestive diseases. Finally, we highlight directions for future research to target L-serine as a promising therapy.