For the past few decades, health officials have been reporting increases in the incidence of autoimmune diseases such as multiple sclerosis (MS). Now researchers at Yale Medical School, Harvard Medical School and the Broad Institute have identified a prime suspect in the mystery - dietary salt.
In the 6 March issue of the journal Nature, Yale researchers showed that salt can induce and worsen pathogenic immune system responses in mice and that the response is regulated by genes already implicated in a variety of autoimmune diseases.
In accompanying papers in the same issue of Nature, researchers from Brigham and Women's Hospital and Harvard identified the key molecular pathway involved in the response to salt, and the Broad Institute sketched out the regulatory network of genes that governs this autoimmune response.
''These are not diseases of bad genes alone or diseases caused by the environment, but diseases of a bad interaction between genes and the environment,'' said Dr David Hafler, the Gilbert H. Glaser Professor of Neurology, professor of immunobiology, chair of the Department of Neurology, and senior author of the Yale paper.
The research was inspired, in part, by an observation that eating at fast-food restaurants tended to trigger an increase in production of inflammatory cells, which are mobilised by the immune system to respond to injury or pathogens but which, in autoimmune diseases, attack healthy tissue.
Researchers at Yale and Germany led by Dominik Mueller wanted to know whether high salt content in diet might induce the destructive immune system response that is the hallmark of autoimmunity.