Published on January 2, 2018
by Anthony L. Komaroff, MD reviewing Wilck N et al. Nature 2017 Nov 30 Relman DA. Nature 2017 Nov 30
When dietary salt intake increases, lactobacilli are lost and blood pressure rises.
Salt-sensitive hypertension is caused, at least in part, by expansion of intravascular volume due to a high-salt diet. In a new study, researchers investigated an additional mechanism: the gut microbiome's response to a high-salt diet.
In mice, a high-salt diet led to depletion of Lactobacillus species, particularly of one Lactobacillusspecies, L. murinus. This was followed by an increase in the number of particular lymphocytes (T-helper [TH]17) that drive many autoimmune diseases and then by a rise in blood pressure. When researchers supplemented the mouse feed with the depleted species of lactobacilli, these changes were reversed.
To examine this phenomenon in humans, 12 healthy nonhypertensive men received slow-release salt tablets in addition to their normal diets for 2 weeks. Several species of lactobacilli became depleted, TH17 lymphocytes increased, and blood pressure rose by the end of the trial.
Previous reports have indicated that the gut microbiome likely plays a role in causing obesity, type 2 diabetes, and atherosclerosis. Now comes evidence of its possible role in salt-sensitive hypertension. In mice and humans, a high-salt diet depletes several Lactobacillus species, activates a lymphocyte subset that is important in autoimmunity, and raises blood pressure. This is consistent with previous reports that a high-salt diet causes flares of experimental autoimmune encephalomyelitis in an animal model of multiple sclerosis and that Lactobacillus-rich probiotics reduce blood pressure in humans. Might we someday treat salt-sensitive hypertension with probiotics?
EDITOR DISCLOSURES AT TIME OF PUBLICATION
Disclosures for Anthony L. Komaroff, MD at time of publication
Harvard Medical School: Harvard Health Publications; Harvard Health Letter
Wilck N et al. Salt-responsive gut commensal modulates TH17 axis and disease. Nature 2017 Nov 30; 551:585. (http://dx.doi.org/10.1038/nature24628)
Relman DA.Microbiota: A high-pressure situation for bacteria. Nature 2017 Nov 30; 551:571. (http://dx.doi.org/10.1038/nature24760)