That gut instinct! Novel insights in the interplay between the microbiota, serotonin metabolism and gut function

The gut microbiota-derived metabolites are evident to have a substantial effect on the regulation of various host functions. Despite the vast number of studies dissecting the host-microbiota interactions over the last years, enormous efforts are still needed to fully unravel the underlying mechanisms of this crosstalk, thereby potentiating the application of microbiota-targeted therapies in clinical practice and in a personalized manner.
This thesis investigates the interplay between the microbiota, serotonin metabolism, and gut function. We showed that a wide range of gut microbiota can convert, the serotonin precursor, 5-hydroxytryptophan into an indole derivative. This bacterial product showed a potent stimulatory effect on the intestinal motility via activation of calcium channels, and a marginal effect on the microbiota composition. Besides, we uncovered the bacterial metabolization of serotonin and how this process impacts both the bacteria and its host. The outcome of this thesis has brought new insight in the physiological role of bacteria-derived indoles and may help the design of novel microbiota-based therapeutics targeting gut motility.