Gut microbiome altered in pulmonary arterial hypertension

Last Updated: 2020-02-26

By Will Boggs MD

NEW YORK (Reuters Health) - The gut microbiome is altered in patients with pulmonary arterial hypertension (PAH), compared with that in healthy controls without cardiopulmonary disease or PAH risk factors, researchers report.

"PAH is not just a disease of the lung and heart," Dr. Mohan K. Raizada of the University of Florida College of Medicine, in Gainesville, told Reuters Health by email. "We have proposed that it should be considered a systemic disease involving complex interactions among multiple organs, particularly the gut, brain, lungs, and heart."

The lungs and the gut share many features related to infection, immunity and epithelial barrier functions, but nothing is known about the potential role of gut microbial communities in patients with PAH.

Dr. Raizada's team used shotgun metagenomics to compare the fecal microbiome of 18 patients with type 1 PAH and 12 healthy matched reference subjects without cardiopulmonary disease.

Alpha diversity, a measure of the richness and evenness of bacteria, was significantly reduced in the gut microbiota of patients with PAH compared with the reference group, the team reports in Hypertension.

Among patients with PAH, there was significant enrichment of the Actinobacteria phylum, including Bifidobacteria, a genus of acetate producers. In contrast, more diverse taxa were enriched in the reference group.

A model that included 30 bacterial species predicted the presence or absence of PAH with 83% accuracy, compared with an expected accuracy of 50% or less were there no association.

"These bacterial genera are different from those seen in gut dysbiosis in hypertensive patients," Dr. Raizada said.

Viral-gene-marker profiles also differed between PAH and reference patients. Multiple Lactococcal phages were enriched within the reference group, but Enterococcal phages were enriched within the PAH samples.

Microbiome alterations in PAH patients were associated with increased arginine, proline and ornithine biosynthesis and interconversion, suggesting a potential role of enzymes and amino acids produced by the gut microbiota in PAH and cardiovascular disease risk.

"Our data suggest that uniquely altered gut microbiome may play an important role in pulmonary pathology and thus present novel targets for both PAH diagnosis and therapy," the authors conclude.

"One can think of fecal matter transplantation, selective probiotics, and/or strategies that target the gut-brain axis for PAH treatment and control if the data can be confirmed by a study with a large cohort," Dr. Raizada said. "These strategies could be used independently or in combination with currently available therapies."

The study had no commercial funding, and the researchers report no conflicts of interest.

SOURCE: https://bit.ly/2SYa6Eq Hypertension, online February 24, 2020.