Gut microbiome, composition tied to hypertension risk in women

Gut microbiome diversity and composition appear to contribute to the development of hypertension in women, suggest the results of a study.

“Our results suggest that targeting the microbiome may be a novel way to prevent or treat hypertension,” the researchers said.

A total of 871 unrelated TwinsUK women with faecal microbiome data (16 s rRNA gene sequencing) were included in the analysis. The association of hypertension with alpha- and beta-diversity metrics was estimated using multivariable linear models adjusted for age, age², and body mass index, as well as MiRKAT models.

The researchers identified taxa associated with hypertension by computing a generalized additive model for location scale and shape, adjusting for covariates and multiple testing. They also replicated results in 448 women from PREDICT-1.

Measures of alpha diversity were significantly lower in hypertensive patients (β, –0.05, 95 percent confidence interval [CI], –0.095 to –0.004; p=0.03), while beta diversity significantly correlated with hypertension (false discovery rate [FDR]<0.05). [J Hypertens 2021;39:1810-1816]

Two genera associated with hypertension had been identified and replicated. The genus Ruminiclostridium 6 was less abundant in hypertensive patients (meta-analysis, –0.31, 95 percent CI, –0.5 to –0.13; p=1x10^-3). On the other hand, the uncultured microbe Erysipelotrichacea-UCG003 was more abundant in hypertensive patients (meta-analysis, 0.46, 95 percent CI, 0.3–0.62; p=1x10^-4).

Genomic analysis of the 16 s rRNA sequence established a 100-percent identity match with the 16 s rRNA sequence of the genus Faecalibacillus. Ruminiclostridium was also functionally annotated, leading to the identification of 83 metabolic pathways, including those previously implicated in blood pressure (BP) regulation.

“For instance, tryptophan biosynthesis and metabolism has been linked to systolic BP, while thiamine metabolism has also been correlated to hypotension in murine models and thiamine supplement studies,” the researchers said. [Nutrients 2020;12:2130; Mol Cell Biochem 2007;299:23-35; Diabetes Metab Syndr 2015;9:213-217]

“Faecalibacillus is a Gram-positive genus, first isolated from healthy South Korean subjects. Due to the novelty of this genus and lack of phenotypic characterization, it was not included in the latest SILVA database, from which we assigned taxonomic ranks,” they noted. [Microbiol Res Announce 2020;9:e01160-e01120; Int J Syst Evol Microbiol 2019;69:2120-2128; Microbiol Res Announce 2020;doi:10.1128/MRA.01160-20]

In addition, previous animal models and case studies showed that members of the Erysipelotrichaceae family significantly increased several inflammatory conditions, including irritable bowel syndrome, colorectal cancer, and rheumatoid arthritis with anticitrullinated protein autoantibodies, suggesting a proinflammatory effect of this bacterial family on the host. [Front Cell Infect Microbiol 2015;5:84; Digestion 2020;102:49-56; Rheumatology (Oxford) 2020;keaa792]

“Previous studies report an association between abundance of Erysipelotrichaceae family members and host lipidaemic profile, particularly relating to cholesterol levels,” the researchers said. “However, after adjusting our analysis for levels of total cholesterol, the association between hypertension and Faecalibacillus remained statistically significant.”

Further research is warranted to further corroborate the association between gut microbiome and hypertension, as well as provide insights into the mechanistic capacity of the gut microbiome to control BP, according to the researchers.