Salt could be one of the reasons why some people develop allergic immune reactions, according to a new German study.
Researchers at the Technical University of Munich (TUM) found that in cell cultures, salt leads to the formation of Th2 cells, which are active in allergic conditions such as atopic dermatitis.
They also detected elevated salt concentrations in the skin of patients.
T-cells are a vital aspect of the body’s resistance to infections, but, if uncontrolled, they can develop pathological responses and attack parts of the body or substances such as allergens.
When that happens, Th2 cells can cause inflammatory skin conditions, such as atopic dermatitis, thanks to the increased production of the proteins interleukin 4 (IL-4) and interleukin 13 (IL-13), according to a study by Professor Christina Zielinski, from TUM’s Institute of Virology.
She said types of T-cells, which should not cause allergies, can turn into Th2 cells when they are in the presence of salt. The changes are reversed when the T cell is again exposed to lower salt levels.
They undertook neutron activation analysis to test skin samples at the Research Neutron Source Heinz Maier-Leibnitz (FRM II) at TUM and at the Institute for Nuclear Chemistry at the University of Mainz and found that the sodium levels in the affected skin areas of patients suffering from atopic dermatitis proved to be up to 30 times higher than in healthy skin.
“The higher sodium levels in the affected skin neatly match another characteristic of atopic dermatitis,” said Prof Zielinski.
"It has been known for some time that patients with this condition have elevated levels of the bacterium Staphylococcus aureus on their skin. These are bacteria, which thrive under salty conditions – in contrast to other commensal bacteria, which are in fact harmed by salt.”
She believes this discovery, coupled with other research, point to a link between salt and the occurrence of atopic dermatitis. However, they do not yet know how the large quantities of salt find their way to the skin.
Matthias J, Maul J, Noster R et al. Sodium chloride is an ionic checkpoint for human TH2 cells and shapes the atopic skin microenvironment. Science Translational Medicine 20 February 2019; doi: 10.1126/scitranslmed.aau0683
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