Beyond the Gastrointestinal Tract: Sex-Specific Skin Microbiota Are Associated With Hypertension in Rats With Genetic Disparities.

Current knowledge of microbiota in hypertension is restricted to the gut and mostly to males. Other than the kidney, the skin is the largest organ playing a role in sodium homeostasis and the mouth is the first site exposed to dietary salt, whereby, we hypothesized that microbiota in these sites associate with salt-sensitive blood pressure (BP). To test this hypothesis, we compared microbiota from the skin, mouth and feces of both male and female young Dahl salt-sensitive (S) rats and 4 genetically disparate congenic strains (RNO1, RNO5, RNO9 and RNO10). Skin microbiota was from 4-6 days old rats before they developed their coats. Oral and fecal samples were collected at 4 weeks old. Microbiota were profiled by 16S rRNA sequencing. Compared to the gut, which is an anerobic site, microbiota from the aerobic skin and oral sites were consistently different in composition across all the strains. Unlike in the fecal samples where Firmicutes and Bacteroidetes were enriched, Cyanobacteria and Actinobacteria were enriched in the skin and oral samples, respectively. Female S rats had greater abundance of skin Cyanobacteria than male S rats. Strain effects were not observed in any of the strains or sites except for RNO5, where a strain × sex × site interactive effect was specifically noted for skin Cyanobacteria. Cyanobacteria contain sodium transporters and are salt-tolerant microbiota, whereby they could potentially regulate sodium excretion and contribute to BP regulation. In summary, our study is the first to discover microbiota beyond the gut as being associated with BP.