A new paper from the lab of Dr Michelle Linterman in our Lymphocyte Signalling programme was published by the journal Frontiers in Immunology. The research examines the potentially beneficial effects that a toxin, produced by bacteria found in the gut, has on the immune system – the group of tissues and cells inside the body that work together to help to prevent infections.

This research, which was funded by US–based organisation Trident Pharmaceuticals, revealed that breathing in part of this toxin can lower the immune system’s response in the lungs of mice. This discovery could be adapted to treat severe allergies as well as autoimmune and inflammatory diseases, where the immune system is over active and causes damage to healthy cells.

A bacteria called Escherichia coli produces toxins that can potentially cause illness in the gut. Enterotoxin subunit B (EtxB) is a part of one of these toxins. On its own EtxB isn’t harmful to cells but researchers have previously shown that it can reduce the activity of the immune system. Dr Linterman’s team have been investigating how this happens and whether it could help to control other illnesses.

One of the greatest challenges with severe allergies can be swelling in the throat and lungs caused by the abnormal activity of the immune system, making it difficult to breathe. This response is called inflammation and it is partially caused by a group of cells from the immune system called T cells. This is why Dr Linterman’s team chose to investigate the effects of inhaling EtxB on T cells in the lungs.

What the team at the Institute have found is that EtxB has two ways to weaken the immune system and prevent T cells from causing inflammation. It can reduce the function of dendritic cells, which normally push the immune system to become more active. Whilst at the same time it promotes cells called regulatory T cells that limit the activation of T cells and so reduce inflammation.

First author on the paper, Dr Alexandre Bignon, said: “It’s interesting to see the effect that ExtB has on our immune system. It’s stopping dendritic cells from activating the immune system whilst using regulatory T cells to shut down the T cells that are already there, it’s a very effective way to stop inflammation happening.”

As the lead researcher on this study, Dr Linterman said: “This work has some great potential, EtxB could become a simple and powerful way of controlling inflammatory diseases. It’s an encouraging basis for the development of fast–acting new treatments.”

This study highlights just some of the complex relationships between cells of the immune system and how they work together to respond appropriately to potential illnesses or infections. By continuing to study how the immune system is controlled we can better understand what happens when things go wrong and find new ways to harness our body’s own defences to prevent or treat diseases.