Biology: Gut microbes worth their salt

High salt intake alters the gut microbiota in mice reports a study published online in Nature this week. As the role of gut microbiota in disease is becoming increasingly recognized, these findings highlight the gut microbiome as a potential therapeutic target to counteract salt-sensitive conditions.

High salt consumption associated with a Western lifestyle can lead to hypertension and cardiovascular disease. It may also drive autoimmunity by inducing pro-inflammatory T helper 17 (TH17) cells, which have also been linked to hypertension.

To determine the effect of high salt consumption on the composition of the gut microbiota, Dominik Muller and colleagues analysed faecal samples from mice fed a normal salt diet (NSD) and a high salt diet (HSD). The authors found that by day 14, several microbial species were significantly decreased in HSD-fed mice. They then used 16S ribosomal DNA gene sequencing and computational approaches to identify the most important bacterial groups that decreased when mice were fed a HSD and found that a member of the genus Lactobacillus (Lactobacillus murinus), was most strongly associated with HSD.

Further work demonstrated that administration of L. murinus to mice reduced TH17 cells and prevented salt-induced aggravation of actively induced experimental autoimmune encephalomyelitis (a mouse model of brain inflammation) and salt-sensitive hypertension. In line with these findings, a small pilot study in healthy humans found that increased salt intake reduces intestinal survival of multiple Lactobacillus species, accompanied by an increase in TH17 cells and elevated blood pressure; although further investigation in humans is required.