First question it was asked the on the Nature site & removed.
What is the relevance of the animal data because if you look at the equivalent dose used in the mice to translate from animals to humans, they need to eat/drink 600g salt a day. Compare this to the average human daily consumption of about 6g a day.
Epub: Kleinewietfeld et al. Sodium chloride drives autoimmune disease by the induction of pathogenic TH17 cells. Nature. 2013 Mar 6. doi: 10.1038/nature11868.
Kleinewietfeld et al. and Wu et al. provide evidence that a high-salt diet can enhance the differentiation of a class of immune cells called TH17 cells, which can exacerbate disease in a mouse model of MS called experimental autoimmune encephalitis (EAE). They also show that mice whose T cells lack the enzyme SGK1 (T-cell SGK−/−) display reduced disease severity and are protected from salt-exacerbated EAE.
The authors demonstrate that salt concentration outside cells and signalling through the IL-23 receptor (cell surface molecules) both influence the activity of SGK1 to drive expression of disease-causing TH17-cells, which include the production of the cytokines (mesages that cells use to communicate with each other) IL-17A and IL-17F and enhanced expression of the IL-23 receptor (IL-23R) and the transcription factor RORγT (encoded by Rorc). Transcription factors are essentially factors that move from the cell into the nucleus to turn on, or off, the expression of genes. However, this finding must be considered in the context of other environmental factors, such as oxygen and nutrient provision. These influence signalling pathways and glucose metabolism in ways that regulate not only TH17-cell differentiation, but also that of other classes of T cells.
“What is the evidence that high salt diet has an effect on human autoimmune disease(s)? I am not aware of any. Should we ignore this study? No we should not! We should probably explore whether or not salt intake is in any way linked to MS disease susceptibility or disease course (prognosis). I will need to speak to my epidemiology colleagues about the feasibility of this study. May be this sort of data is being collected in other studies and the question can be asked from existing data sets. Any suggestions or insights?”
This study indicates that high salt concentrations induce a Th17 response and augment autoimmunity. There was no dose-response and so we don’t know if a low salt diet was protective.