The background

It is known that problems with the blood-brain barrier (BBB) and the immune system contribute to the damage seen in multiple sclerosis (MS). These problems are often worsened by oxidative stress, a process in which there is an imbalance between harmful oxygen species (called free radicals) and antioxidants.  For these reasons, current MS therapies aim to target these issues (particularly by lowering the immune response) to help prevent further damage.  However, whilst they can be highly effective in many people, these therapies don’t work for everyone and also come with side-effects.

With this in mind, more research is being done into potential lifestyle factors that can be used to help manage MS. As an example, exercise has been shown to provide many physical and cognitive benefits for people with MS (such as reduced fatigue and improved quality of life).  Recent studies showed that exercise can lead to the production of a molecule (BDNF) that has a protective effect on nerves in both animal models and people with MS. However, little is currently known about how exercise might effect the immune system or the blood-brain barrier in people with MS.

The study

Researchers from UNESC and UFSC in Brazil undertook a study to get a better understanding of the effects of exercise in MS.  To do this, mice were split into four groups:

  1. Healthy mice
  2. Mice with EAE (the animal model of MS)
  3. Mice with EAE + strength training
  4. Mice with EAE + endurance training

The clinical progression of the mice was observed over time to determine whether disease had worsened.  Samples were also taken from the mice so that levels of oxidative stress, inflammation and BBB permeability could be measured.

The findings

Using this method, the researchers were able to make the following conclusions:

  • Exercise reduced the clinical progression of mice in both the strength training and endurance training groups compared to mice with EAE.  It appeared as though endurance training led to a slightly better outcome.
  • Mice with EAE were shown to have higher levels of oxidative stress than healthy mice.  This oxidative stress could be reduced (almost back to the levels seen in healthy mice) by both forms of exercise.
  • Chemical messengers, known as cytokines, that promote inflammation were increased in mice with EAE compared to healthy controls.  The levels of most of these were returned to normal through both exercise programs.
  • When comparing the effects of EAE on the blood-brain barrier, two problems were observed.  Firstly, proteins involved in holding the BBB together (known as tight junctions) were decreased in mice with EAE compared to healthy controls.  Secondly, molecules involved in helping move immune cells into the brain (called adhesion molecules) were increased.  Exercise had a positive effect on both of these problems.

The outcomes

This study contributes to the growing evidence that exercise can have positive effects in multiple sclerosis.  In this article, it has been shown that the benefits of exercise may be due to a number of factors – including decreasing oxidative stress, reducing inflammation and improving the function of the blood-brain barrier.

As these studies have been performed in an animal model, it will be interesting to see whether they are replicated in people with MS.  Considering people with MS will have a varying ability to exercise, it is important that more work is done in this area to understand how the benefits are achieved and to determine the best types of exercise for people to undertake.

The abstract for this article can be viewed here.

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