Ultraviolet light (UV) can prevent both the development and progression of autoimmune diseases, especially MS. However, despite the clear health benefits that would arise from understanding how increasing the amount of UV we receive leads to a reduction in MS, the mechanisms by which UV provides this protection remains a mystery. One well known event to occur after UV exposure is the synthesis of vitamin D in the skin. However, recent studies suggest that there is something else about UV exposure that explains the protective properties of sunlight. Dr Byrne is investigating whether UV suppresses the immune system independently of vitamin D and whether this is responsible for the protective effect of sunlight on autoimmune disease. Identifying the mechanism by which UV suppresses immunity may provide the potential to replicate this for use as an autoimmune therapy.
Dr Byrne has showed that UV exposure in a laboratory model of MS protected against development of disease. He then went on to show this protection was mediated by the activation of particular cells associated with the signalling molecule interleukin-10. B regulatory cells are able to inhibit harmful immune responses by interacting with T cells (the cells thought to be responsible for MS disease) and by releasing interleukin-10. Dr Byrne and his team believe the activation of the B regulatory cells is the most likely mechanism by which sunlight protects internal organs from autoimmune attack in MS.
The activation pathway of B regulatory cells is thought to be mediated by mast cells, immune cells which have a well-known role in inflammation and allergy. The next step will be to determine whether human mast cells are capable of activating human B regulatory cells. Dr Byrne has established a collaboration with Dr Michele Grimbaldeston at the Hanson Institute in Adelaide to investigate whether these findings can be extended to humans. The replication of these pathways in human cells is a first step towards cellular immunotherapy for people with MS. Dr Byrne has also used the extensive preliminary findings of this study to apply for an NHMRC grant in 2012.
Updated: 30 June 2012
Updated: 03 January, 2011