The conventional wisdom is that sodium chloride consumption is too bad for you. Diets high in salt have been linked to high blood pressure, cardiovascular disease, and even autoimmune disorders. But a new study shows that dietary salt may also have effects boost the immune system. The researchers report that high levels of salt in the skin using mouse fight bacteria and humans may also constitute salt stocks on sites of infection.
"The idea that salt storage could have evolved for the host defense is very exciting," says Gwen Randolph, an immunologist at the University of Washington in St. Louis, which does has not participated in the study. "It's almost so new that it is difficult to swallow. I think it will take some time for the immunology community to allow this concept to take hold. "
The scientists recently learned that the connective tissue of the skin can serve as a reservoir for the sodium ions when we consume large amounts of salt. When Jens Titze, a clinical pharmacologist at the School of Vanderbilt University in Nashville medicine and lead author of the study, studied the salt intake in mice, he noticed that even the mice on the diet low salt concentrations had abnormally high salt in the injured skin . Titze and his colleagues realized that the immune cells that arrive in injured skin fight infection entered a salty microenvironment. They hypothesized that the body was hanging salt on the infected skin to protect against invaders. in other words, "we Salting our cells to protect us," said Jonathan Jantsch, a microbiologist at the University of Regensburg in Germany and lead author of the study, which appears in the current issue of cell Metabolism .
whether all that extra sodium chloride or interfered help immunity, researchers have turned to macrophages, an immune cell that engulfs and digests invading pathogens. Activated macrophages kill invading microbes by releasing molecules called reactive slaying oxygen species, and the team thought that high concentrations of salt could trigger immune cells to produce these compounds. The team macrophages cultured mouse and salt sprinkled in the bath of nutrients until the cells were growing at a concentration equivalent of sodium chloride at what they had seen in the skin infected by rodents. Salt has increased the ability of immune cells, the team reports microbe-killing; macrophages exposed to high concentrations of sodium chloride released much microbicidal molecules than those who grew up in a salt-free culture medium. Then the team infected macrophages with common pathogens Escherichia coli or Leishmania major . After 24 hours, the E. coli load in macrophages exposed to high concentrations of sodium chloride is less than half that macrophages cultured without salt and major L. infections decreased as well.
To test whether increased consumption of salt enhances the immune system in live mice, the researchers fed one group of mice a diet high in salt and the other a low-salt diet for 2 weeks and infected skin on the footpads of rodents l. major . For the next 20 days, both groups of mice showed significant swelling in their footpads that keep the infection, regardless of diet. After this period, however, the mice on salt-rich diet improved healing with less foot lesions and parasite load lower than the group eating poor food salt.
"[The experiments] demonstrate that the extremes of salt consumption results of additional salt accumulation in the infected skin and stimulate the immune experimentally," says Jantsch.
humans, the group found evidence that salt accumulation can be localized to sites of infection. Using a new MRI technique that measures the sodium in the skin, the team found abnormally high levels of salt accumulation in bacterial skin infections of people, if they consume a diet high in salt.
Taken together, the group's findings indicate that mice and humans can enjoy a salt boost resulted in immune defense. But do not start charging more salt on your chips just yet. "The only thing you do not want to draw from this study is that it allows you to eat more salt to improve immunity," says Randolph. A high salt diet may have been a useful way to fight against infections our ancestors, before antibiotics existed we lived long enough to develop heart disease, but today, the harmful effects of a diet high in salt outweigh the immunological benefits, according to Jantsch. the increasing the concentration of salt in the infected skin from outside the body by charging the tissue with salt intravenous fluids, gels wounds or bandages, may be a potential for a more realistic implementation of the results, said -he.
additional research is needed before such treatments are possible, but the results "raise the possibility that this relatively simple mechanism might be able to improve or promote immunity," explains Thomas Coffman, a nephrologist at the medical Center of Duke University in Durham, North Carolina. "It is very challenging from this point of view."
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