Salt may be risk factor for MS, other autoimmune diseases

Scientists from some of the country's leading research institutions think they've found a trigger for autoimmune disorders like multiple sclerosis, which have been increasing in frequency over the past few decades.

The culprit can more than likely be found on your kitchen table--salt. Researchers at the Yale School of Medicine, Harvard Medical School, the Broad Institute's Klarman Cell Observatory, Brigham and Women's Hospital and the Massachusetts Institute of Technology have observed that in mice, salt can provoke and worsen pathogenic immune system responses that are regulated by genes already associated with a variety of autoimmune disorders.

"We know that autoimmune disorders are rising at an alarming rate, and we know this can't be caused by genes because genes can't change that quickly," said researcher David Hafler, a professor of immunobiology and chair of Yale's department of neurology, to FierceBiotechResearch.

Hafler and other researchers first noticed the link between salt and inflammation in cells in a pilot project of 100 individuals in which participants who frequently ate at fast-food restaurants had an increase in the production of inflammatory cells.

Their research shows that the growth of a type of immune cell--known as a T helper 17 or Th17 cell--influences the development of immune responses. Th17 cells can promote inflammation that is important for protection against pathogens, and the cells are also thought to play a key role in diseases like multiple sclerosis, psoriasis, rheumatoid arthritis, and ankylosing spondylitis, an inflammatory disease that affects the joints between the spinal bones and those between the spine and pelvis.

Researchers found that adding salt to the diet of mice induced production of these Th17 cells. More strikingly, mice on high-salt diets developed a more severe form of an animal version of MS, called experimental autoimmune encephalomyelitis. Their research appears in three companion papers in the journal Nature.

Hafler says this does not suggest that salt is the only trigger for autoimmune diseases, but it could provide a new window into studying the interplay between environmental factors and genetics in autoimmune disorders. Obesity, smoking and vitamin D deficiency are also believed to be risk factors for developing autoimmune disorders.

"We have to be conscious of overinterpretation of the mouse data," Hafler said, adding that translating research from an animal study to a clinical trial takes time.

The next step for the researchers is to conduct a clinical trial in which patients with diseases like MS and acute hepatitis will be given a low-salt diet, Hafler says. The findings could ultimately impact how autoimmune disorders are treated.

- read the Yale news release
- here's the press release from Harvard and the Broad Institute
- check out the story in Nature