Key Autoimmune Disease Cells Within The Thymus Dynamically Change Over Time

The immune system plays a crucial role in both health and disease. From recovering from an infection to helping a wound heal, the immune system is always playing its part. Although irregular, excessive and ultimately damaging activation of the immune system can be a consequence of an autoimmune disease.

There are many different autoimmune diseases that affect the body in different ways. These range from rheumatoid arthritis, which affects the joints, to multiple sclerosis which affects the nerves of the brain and spinal cord.

A major feature of autoimmune diseases is chronic inflammation which has been strongly associated with a certain class of immune cell – innate lymphoid cells (ILCs). There are 3 forms of ILC which are simply termed ILC1, ILC2 and ILC3; for group 1 ILCs and so forth. Each of these ILC groups has distinct roles and has similar behaviour to T cells.

Innate Lymphoid Cells

To understand the role of this cell type in relation to immune-mediated disease a group of researchers from the Rheumatoid Arthritis Centre of Excellence (UK) have published research establishing the number of different ILCs in the thymus and how these change from embryo to adulthood.

Lead author of the publication, Rhys Jones, explained why the research was needed,

“While the importance of ILCs outside of the thymus is well described, our understanding of these cells within the thymus remains largely unknown. There are many sub-types of ILC and previous studies have reported ILC3 to be the main ILC population within the adult thymus where they provide key signals that help regenerate thymic tissue following damage, whereas we have discovered ILC2 to be the main ILC population within the adult thymus.”

The group’s research included the use of cell and mouse models to track changes in thymus ILC sub-types throughout a lifespan. They found that sub-types of ILCs change dynamically throughout mouse development from embryonic stages to maturity, including a prevalent population of ILC2 cells.

Significance

Jones noted the significance of the findings,

“The thymus has a fundamental role in T cell education and prevents self-reactive T cells from entering the periphery. By furthering our understanding of ILCs within the thymus we are able to investigate their contribution to the set-up of the thymic architecture that is important to potentially prevent the development of autoimmune diseases.”

Through discoveries like this it is possible to both better understand autoimmune diseases, and also to edge closer to finding treatments for these diseases. Whilst these discoveries establish the dynamic shifts in ILC sub-types in the thymus, it is important to also decipher the effect that this has on other cell types and on autoimmune disease as a whole.

Jones also outlined where this research could be developed upon in the future,

“An exciting next step for us is to build on the data presented in our paper to identify the contribution these cells make within the thymus; both in adulthood and throughout development.”

The translational impact of discovery science research in this area will hopefully lead to better outcome for patients of multiple auto-immune diseases and reduce the current healthcare burden from this area.

Rhys Jones, Emilie J. Cosway, Claire Willis, Andrea J. White, William E. Jenkinson, Hans J. Fehling, Graham Anderson and David R. Withers
Dynamic changes in intrathymic ILC populations during murine neonatal development
European Journal of Immunology. 31 May 2018. https://doi.org/10.1002/eji.201847511

Author: Geoffrey Potjewyd; Regenerative Medicine & Neuroscience PhD student at the University of Manchester. Image: Normal thymus. Credit: Wellcome Collection. CC0