Sheep Disease Toxin Shines a Light on MS

In a recent study, those with multiple sclerosis were found to be more likely to harbor antibodies for a disease toxin normal found in sheep.

Multiple sclerosis (MS) affects an estimated 2.3 million people worldwide. MS affects the central nervous system (CNS) and can cause a range of symptoms – often involving problems with movement, sensation, balance, and vision.

Symptoms generally appear when an individual is in their 20s or 30s. Some can be managed, and, in some cases the progression of the disease can be slowed. However, there is still no cure. MS in an autoimmune disease, in which the immune system attacks otherwise healthy tissue – in this case, the CNS. Why the immune system should turn on itself is still not understood. Despite decades of work, the exact cause of the disease is still shrouded in mystery, though both genetic and environmental factors are thought to be involved.

Recently, a group of researchers at the University of Exeter in the United Kingdom looked for clues about MS’s origins in a surprising place: sheep.

The first clues that sheep might provide some insight into MS came in 2013, when a team in the U.S. noticed that some people with MS had increased levels of antibodies to a toxin known as epsilon toxin (ETX). This toxin is produce by the bacterium Clostridium perfingens, found in the guts of livestock – most commonly in sheep.

ETX crosses the gut wall and builds up in the kidneys and brain. And, once in the brain, it destroys both the myelin that coats nerves and the cells that produce myelin. In sheep, this type of ETX poisoning is called enterotoxaemia, or pulpy kidney disease.

In MS, myelin and the cells that produce it are destroyed by the immune system. This striking similarity between enterotoxaemia and MS makes any potential relationship worth investigating further.