But Kuchroo and other researchers say that evidence so far cannot predict the effect of salt on human autoimmunity. “As a physician, I’m very cautious,” Hafler says. “Should patients go on a low-salt diet? Yes,” he says, adding that “people should probably already be on a low-salt diet” for general health concerns.
Other experts are intrigued by the findings. “They have a very clear effect in vitro,” says John O’Shea, scientific director of the National Institute of Arthritis and Musculoskeletal and Skin Diseases Intramural Research Program in Bethesda, Maryland. But Hafler and others note that there are likely many cell types and environmental factors involved in triggering autoimmunity.
The results offer tantalizing leads for drug targets for autoimmune conditions. But O’Shea notes that it is unclear whether TH17 proliferation is a factor in all autoimmune disease. A targeted drug that might work to relieve psoriasis might not subdue rheumatoid arthritis. “When we say autoimmunity, we’re implying that it’s one thing,” O’Shea says. “But it’s not one thing — it’s heterogeneous.”