Gut microbes as modulators of the neuro-immuno-endocrine system

The gut microbiota is highly integrated into the biology of the host, influencing adaptive responses and regulating multiple physiological systems. In particular, recent studies of the microbiota–gut–brain communication axis have provided us with a deeper understanding of the relationship between microbes and host, revealing a key role for this pathway in the maintenance of homeostasis. Intestinal microbes influence development of the central nervous system (CNS) and stress responses; can modulate peripheral and central neural function and alter behaviour.Composition of the gut microbiota is also an important influence on immunity and there is clear evidence for the direct modulatory effects on immune cells. However, the realization that the intestinal microbes can alter neural and endocrine components of gut–brain communication that, in turn, regulate immune responses, opens the possibility that changes in neuroendocrine environment may contribute to effects of gut bacteria on systemic immunity. Furthermore, gut bacteria can act on specific targets that are common to nervous, endocrine and immune systems and thus may be key to microbial regulation of host adaptive responses.While the concept of microbiota–gut–brain immune communication is largely unexplored, future studies in this area will help us identify the potential for microbial-based therapeutic strategies to maintain immune homeostasis.

Graphical abstractThe gut microbiota is integrated with the neuro-immuno-endocrine super-system.Figure optionsDownload full-size imageDownload as PowerPoint slide