In MS, myelin, the material that surrounds and protects nerve fibres, is damaged in the brain and spinal cord, and so are the cells that make myelin, called oligodendrocytes. The attack on myelin is driven by specific immune cells called T cells. A subset of T cells, known as T regulatory cells, or Tregs, have the ability to regulate or suppress the immune attack. In people with MS, however, Tregs have been shown to be less able to perform this helpful function. Previous research has indicated a possible role of Tregs in tissue regeneration, so this team explored how Tregs might promote regeneration of myelin.
First, the team deleted Tregs from a mouse model in which myelin is damaged and then spontaneously repairs. In this model, immature oligodendrocytes were generated, but failed to mature into myelin-making cells. Formation of new myelin was substantially impaired. Administering Tregs to the mice, however, replenished the supply of mature oligodendrocytes.
Then, the team examined whether Tregs could promote myelination in healthy mouse brain tissue isolated in the laboratory. Oligodendrocytes and myelin formation increased in tissue treated with Tregs, significantly more than control tissue without them. Because there is no inflammation in this model, this suggests the Tregs were doing something directly to the oligodendrocytes to promote myelin repair.
Importantly, the team also pinpointed a specific protein, CCN3, which was produced by Tregs and appeared to be responsible for enhancing myelin regeneration. Although prior research has suggested a role for CCN3 in tissue regeneration, this is the first report of its role in the central nervous system, and the first report showing that Tregs produce this regenerative protein.
If the results are confirmed through further research, these basic laboratory studies could eventually be translated to promising new therapeutic approaches to stimulating myelin repair to restore function in people with MS.
This article was adapted from: http://www.nationalmssociety.org/About-the-Society/News/Researchers-Uncover-Molecule-Secreted-by-Immune-Ce