Photo: Blue sky with sunshine and a few clouds

New insights into the role of vitamin D in our immune system

New research shows that vitamin D is associated with a reduced immune response – which has implications for autoimmune conditions like MS.

The link between vitamin D and MS

We know vitamin D is linked to MS. But we still don’t fully understand how. This research sheds some light on the relationship between vitamin D and the immune system, and the mechanisms involved.

Professor Richard Mellanby, from the University of Edinburgh’s Centre for Inflammation Research, said: “Low vitamin D status has long been implicated as a significant risk factor for the development of several autoimmune diseases.

“Our study reveals one way in which vitamin D metabolites can dramatically influence the immune system.”

Vitamin D reduces immune cell activity

Researchers at the University of Edinburgh looked at how vitamin D affects two types of cells, called dendritic cells and T cells. These cells are both part of our immune system.

Normally, dendritic cells activate T cells, which play an important role in fighting infections. But in MS, these T cells attack the body’s own tissues – leading to the damage associated with MS.

By looking at cells from mice, researchers found that vitamin D caused dendritic cells to produce more of a molecule called CD31. And CD31 was then shown to reduce the ability of dendritic cells and T cells to form a stable connection. Without this connection, dendritic cells were unable to activate T cells, resulting in a reduced immune response. These effects were also seen in human cells.

These results, published in Frontiers in Immunology, suggest that low levels of vitamin D may lead to more T cell activation – and therefore an increased immune response. This could influence the risk of autoimmune conditions like MS.

Our vitamin D research

It’s not known if people living with MS in the UK are vitamin D deficient, or whether vitamin D supplements could be used to manage MS.

We’re funding Dr Ruth Dobson, at St George’s University of London to take us a step closer to answering this question. Ruth and her team will collect blood samples from people with and without MS, to accurately map vitamin D levels in people with the condition across the UK. Saliva samples will also be collected to see if a person’s genetic makeup can affect their vitamin D levels, and the impact this may have on taking supplements.

It’s hoped the results of this project will inform any future trial of vitamin D as a DMT for MS.