Salt linked to immune rebellion in study

The amount of salt in our diet could be involved in driving our own immune systems to rebel against us, leading to diseases such as multiple sclerosis, early laboratory findings suggest.

Several teams of scientists have simultaneously published data in the journal Nature suggesting a link.

Salt may activate a part of the immune system that can target the body.

Experts said the findings were very interesting and plausible, but were not a cure for people with MS.

The body's defence against infection can go horrible awry, turning on the body and leading to autoimmune diseases including Type 1 diabetes, rheumatoid arthritis and multiple sclerosis.

Genetics is thought to increase the risk of such diseases, but the world around us also has a major impact. One of the leading theories behind multiple sclerosis is a viral infection, but smoking and a lack of vitamin D may make the condition more likely.

Now researchers believe they have the first evidence that the amount of salt in our diet may also be contributing.

Gene link

Teams of researchers at the Brigham and Women's Hospital and the Broad Institute of MIT and Harvard were investigating a part of the immune system that has been implicated in autoimmune diseases.

We were all really quite surprised to see how changes in dietary salt could have such a profound effect”

Prof David Hafler
Yale University

They wanted to know how T-helper 17 cells were produced.

A sophisticated analysis of the complicated chemistry needed to form a T-helper 17 cell - which involved carefully monitoring cells and reverse engineering the changes - identified a critical gene. But the gene had been seen before.

"Its day job is to increase salt uptake in the gut," said Dr Vijay Kuchroo from Brigham and Women's Hospital. "When we put extra salt in the culture dish it was one of those 'Aha' moments, the cells were becoming T-helper 17 cells."

Mice fed a high-salt diet were more likely to develop a disease similar to MS in experiments.

Meanwhile, researchers at Yale University were also investigating salt and looking at human cells.

David Hafler, professor of immunobiology at Yale, told BBC news online: "In mouse models of MS, those fed high-salt diets had significantly worse disease.

"We were all really quite surprised to see how changes in dietary salt could have such a profound effect."

Advice?

There is caution about over-interpreting what is very early research. Studies are now taking place in people with high blood pressure, also caused by high salt intake, to see if there is a link between salt and autoimmune diseases in people.