Research in the laboratory of Dr Michelle Linterman at the Babraham Institute ‘s Lymphocyte Signalling programme has provided fresh insights into the potentially beneficial effects that a toxin, produced by bacteria found in the gut, has on the immune system.

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.

The 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.

One of the bacteria that can cause illness is Escherichia coli, which produces toxins that can potentially cause illness in the gut.

Enterotoxin subunit B (EtxB) is a part of one of these toxins but on its own isn’t harmful to cells. 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.

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.”

Lead researcher 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.”