Study sheds light on link between gut microorganisms and nervous system

08 January 2015

Human anatomy - highlighted intestines

Glial cells support nerve cells throughout our bodies. Researchers have now found that, in our gut, the proper organisation of glial cells depends on the presence of the microorganisms that live there - and these cells play an important role in responding to changes in the make-up of these microorganisms. 

The findings, from the Medical Research Council's National Institute for Medical Research (NIMR; now part of the Francis Crick Institute), help to explain how changes to gut microorganisms such as after antibiotic treatment or recurrent intestinal infections can predispose people to bowel disorders.

Dr Vassilis Pachnis from NIMR explained: "Our intestine is inhabited by a vast number of microorganisms, known collectively as microbiota. We have a symbiotic, or mutually beneficial, relationship with these microbial communities. There's clear evidence that they influence the function of several organs including our brain, but we don't yet understand how this happens.

To shed light on the issue, the scientists studied the interaction between the neural networks in mouse intestines and the microbiota inside their gut lumen.

Surprisingly, the team found that the networks of neurons and glial cells in the intestine are highly dynamic and can reorganise themselves in response to changes in gut microbiota.

They showed that these glial cells are continuously renewed - and that this replenishment depends on the presence of the microbiota. When the scientists reared mice in sterile conditions (with no microorganisms present), no glial cells developed in the mucosa, the innermost layer of the gut that is closest to the intestinal contents. And when the team treated adult mice with antibiotics, these glial cells were lost.

The findings suggest a possible mechanism for communication between the inside of the gut, the enteric nervous system and the brain.

Dr Pachnis said: "Our findings could have far-reaching implications. Previous studies have shown that glial cells in the enteric nervous system play a crucial role in maintaining balance by keeping the fitness of the intestinal epithelial barrier - a layer of cells that protects the inside of our bodies from the often harmful contents of the intestine -and by regulating the immune responses of the gut. Our current experiments extend these studies and demonstrate that glial cells in the intestine are well positioned to sense and respond to changes in the gut microbiota.

"Therefore, our work provides a rational explanation as to why changes in the composition of gut microbiota, such as following the extensive use of antibiotics or recurrent intestinal infections, could affect the organisation and function of the enteric nervous system and beyond and predispose people to bowel and other disorders.

"The next step is identifying and characterising the signals used for communication between the microbiota and the enteric glial cells. This could lead to the development of new treatments to help protect the enteric nervous system, and in particular its glial cells, against disease-causing microorganisms and inflammatory gut conditions."

The paper, Microbiota controls the homeostasis of glial cells in the gut lamina propria, is published in Neuron.

  • Scientists at the National Institute for Medical Research (NIMR) have shed light on the link between gut microorganisms and nerve cell networks in our intestines. It's hoped that the findings will lead to new treatments to protect against bowel infections and inflammatory conditions. 
  • Our enteric nervous system is part of our peripheral nervous system, which connects the brain and spinal cord to our limbs and various organs throughout the body. The enteric system is made up of a vast network of interconnected nerve cells (neurons) embedded within the gut wall. These neurons are supported by a type of cell called glial cells. Glial cells are found alongside neurons everywhere in our bodies, including our brain, spinal cord and peripheral nervous system. 
  • The NIMR scientists worked with colleagues at Queen Mary University in London, Nanyang Technological University in Singapore, the Karolinska Institute in Stockholm, Sweden, and the Hubrect Institute in Utrecht, The Netherlands.