There is growing interest in the link between the gut and MS. Ongoing research has uncovered strong evidence for a disturbance of gut physiology underpinning autoimmune disorders such as inflammatory bowel disease and Type I diabetes, and new evidence is suggesting this list may also include MS.
A recent study from Swedish researchers at Lund University have identified new evidence for a link between the integrity of the gastrointestinal tract and the severity of illness in an animal model of MS. The walls of the gastrointestinal tract act as a barrier between the body and the outside environment. A loss of this protective function has a large effect on the immune system, and may be involved in the development of autoimmunity.
In this study, the researchers measured how permeable or porous the walls of the intestines are by measuring the levels of gastrointestinal markers in the blood stream. Increased permeability of intestine walls reduces the ‘barrier’ between the internal and external environments, and allows unregulated travel of foreign molecules and cells from the gastrointestinal tract into the bloodstream.
The team not only identified dysfunction in the intestinal barriers in mice with MS-like illness, but also found that increased permeability of the intestinal walls was present prior the onset of clinical signs of disease in these mice, and that the permeability worsened as the disease progressed. The mice also had signs of structural abnormalities and decreased thickness of the intestinal walls.
By studying the protein levels in the intestinal wall cells, the researchers found excess levels of a protein known to be involved in regulating transport of nutrients and other material across the intestinal walls, which were present before illness onset. The team also found an abnormal imbalance of pro-inflammatory immune T cell populations, and suggest that the intestinal damage may be immune-mediated.
Bringing all of these findings together, the team report a relationship between intestinal wall integrity, immune activity within the intestines, and symptom severity in mice with MS-like illness. This suggests that gastrointestinal dysfunction may be related to MS disease progression and could thus be a target for new therapies aiming to halt the disease. Further study is needed to demonstrate if similar effects are observed in humans with MS, and whether these effects have any influence on MS disease severity or course.
As well as investigating the integrity of the gut wall and how it is influenced by and interacts with the immune system, researchers around the world are also investigating how the profile of bacteria that occupy the gut may also influence autoimmune diseases. Australian researcher Dr Stuart Smith was awarded an MS Research Australia Incubator Grant in 2013 to study the profile of gut bacteria in people with MS. You can read more about this project here.