The effects of visible light wavelengths on regulatory T-cells
Research type
Research Study
Full title
The effects of visible light wavelengths on regulatory T-cells
IRAS ID
259464
Contact name
Wayne Thomas
Contact email
Sponsor organisation
University Hospitals Plymouth NHS Trust
Duration of Study in the UK
0 years, 1 months, 1 days
Research summary
There is evidence that night shift work has a negative effect on human health. This study looks at one aspect of night shift work, the exposure to light, and whether this light affects our regulatory T cells.
Our immune system comprises many types of specialised cells that are important in fighting infections caused by pathogens (eg. bacteria, fungus or virus). The immune system and these cells are also involved in autoimmune diseases (e.g. rheumatoid arthritis) and cancer. Autoimmune diseases are when the body inappropriately reacts to ‘self’, our own proteins, which can cause damage to our body. Cancerous cells are our own cells that are ‘out of control’ and ideally should be recognised by the immune system. There is a constant balance to be maintained between our immune system overreacting and not reacting enough. To achieve this balance there are signals that cells can send to upregulate or downregulate the immune system according to the situation our body is in. T cells are a type of immune cell that can be further broken down into subtypes: cytotoxic T cells, helper T cells and regulatory T cells (Tregs). These subtypes have distinct functions within our body. Cytotoxic and helper T cells are involved in killing or deactivating pathogens. Tregs are immune cells that have a role in regulating other cells of the immune system, including the other types of T cells. They can help ‘switch off’ or ‘downregulate’ the immune system, also known as immunosuppressive activity. The immunosuppressive activity of regulatory T cells is important in the prevention of autoimmune diseases, but can also contribute to cancer progression.
UV light is used to treat skin conditions such as eczema and psoriasis, and cutaneous T cell lymphoma. Therapeutically this is given in adults with psoralens (a photosensitising agent) which sensitise the T cells. However, from paediatric studies where psoralens are not used there is also evidence that UV light exposure alone can have clinical efficacy. There is evidence from the use of UV light treatment that the activity of Tregs is affected by exposure to this wavelength of light. Are Tregs affected just by exposure to these wavelengths of light? Most of the wavelengths of visible light are absorbed by skin except red light which passes through much more easily. Haemoglobin is a major absorber of light energy so clearly some visible light reaches the vascular dermis. There is emerging evidence that disruption of the circadian rhythm (our natural body clock) has adverse effects upon humans. The American Medical Association has designated night shift working as a carcinogen. Is this just because of disruption of our circadian rhythm or is it because our Tregs within our body are encountering continued exposure to light rather than periods of time in darkness? One simple way to answer this question is to remove the effect of the disruption of circadian rhythm and just expose Tregs for a period of time to darkness or a variety of wavelengths of light.
REC name
London - West London & GTAC Research Ethics Committee
REC reference
19/LO/0270
Date of REC Opinion
5 Feb 2019
REC opinion
Favourable Opinion