medwireNews: Results from two studies published in Nature show that eating a salty diet may trigger the development of autoimmunity.
Researchers found that increased physiologic salt concentrations stimulated production of highly proinflammatory interleukin (IL)-17 producing T helper (TH17) cells in mouse and human cells.
They also found that mice fed a high salt diet produced increased numbers of pathogenic TH17 cells and developed a more severe form of experimentally induced autoimmune encephalomyelitis than mice not fed a high salt diet.
"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 senior author of one of the studies David Hafler (Yale University, New Haven, Connecticut, USA) in a press statement.
"Thus, increased dietary salt intake might represent an environmental risk factor for the development of autoimmune diseases through the induction of pathogenic TH17 cells," write Hafler, fellow Yale University researcher Markus Kleinewietfeld, and colleagues in their paper.
The second study, carried out by Aviv Regev and Vijay Kuchroo from the Broad Institute of MIT and Harvard in Cambridge, Massachusetts, USA, evaluated the mechanism through which the pathogenic TH17 cells are produced in response to salt exposure.
They found that a moderate increase in salt concentration stimulates serum glucocorticoid kinase 1 (SGK1) production. SGK1, a protein kinase that plays an important role in the cellular response to stress, seems to be a critical regulator of IL-23 that helps it induce production of pathogenic TH17 cells that could go on to cause autoimmune disease.
Writing in a linked news and views article, John O'Shea (National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, Maryland, USA) and Russell Jones (McGill University, Montreal, Quebec, Canada) say that it may be premature to say that eating too much salt can trigger autoimmune disease as many other factors such as cytokines, microorganisms, diet, and metabolism also influence T-helper cells.
"However, the work should spur investigation of tangible links between diet and autoimmune disease in people," they comment.
"In doing so, it will be essential to conduct formal, controlled clinical trials. Fortunately, the risks of limiting dietary salt intake are not great, so it is likely that several such trials will be starting soon."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Helen Albert, Senior medwireNews Reporter