[Role of the Vagus Nerve in the Gut-Brain Axis: Development and Maintenance of Gut Regulatory T Cells via the Liver-Brain-Gut Vago-Vagal Reflex].

The vagus nerve is considered a key component of the gut-brain axis, a complex network which connects the gut and the brain bidirectionally. The vagus receives a variety of information from the gut and transmits it to the brain. We recently discovered that peripheral regulatory T cells (pTregs) in the gut, which are essential for intestinal immune tolerance, are not only controlled by the gut microbiota but are also regulated by the vago-vagal reflex via the gut microbiota information→gut→liver→brain→gut pathway. The discovery of the role of the gut-brain axis in the intestinal pTreg cell induction mechanism may be useful for the development of a neurostimulatory therapeutic tool to coordinate the complex intestinal-brain association via the brain. Additionally, in this review, we have summarized reports that describe the correlations between the vagus and the gut-brain axis, which have been discovered successively.