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Specific Gut Bacteria May Be Associated With Pulmonary Arterial Hypertension
February 24, 2020

Researchers have identified a distinct collection of bacteria found in the gut that may contribute to and predict the development of pulmonary arterial hypertension (PAH), according to a study published in Hypertension.

“We showed for the first time that specific bacteria in the gut are present in people with PAH,” said Mohan Raizada, PhD, University of Florida, Gainesville, Florida. “While current PAH treatments focus on the lungs, looking at the lung/gut axis could open the door to new therapies centred in the digestive system.”

For the study, Seungbum Kim, PhD, University of Florida, and colleagues collected stool samples from 18 patients with PAH and 13 people without a history of cardiopulmonary disease. The microbiota DNA from the stool samples were isolated and sequenced.

The researchers observed significant taxonomic and functional changes in microbial communities in the PAH cohort. Pathways for the synthesis of arginine, proline, and ornithine were increased in patients with PAH compared with controls.

Additionally, groups of bacterial communities associated with trimethylamine/ trimethylamine N-oxide and purine metabolism were increased in patients with PAH.

In contrast, butyrate-and propionate-producing bacteria such as Coprococcus, Butyrivibrio, Lachnospiraceae, Eubacterium, Akkermansia, and Bacteroides were increased in controls.

Virome analysis showed enrichment of Enterococcal and relative depletion of Lactococcal phages in patients with PAH.

Ultimately, having a specific microbiota profile in the gut predicted the presence of PAH with 83% accuracy.

This is the first link between a specific collection of bacteria and PAH.

“We were very surprised to see such an association within a small group of study subjects,” said Dr. Raizada. “It usually requires hundreds of patients to achieve such significance.”

While gut microbiota are constantly changing, depending on food consumption, environmental factors, and genetic makeup, the bacteria associated with PAH do not seem to change, according to Dr. Raizada.

If the results are validated in a larger study, the researchers said that the unique bacterial profile could help to diagnose PAH early, possibly replacing the invasive heart catheterisation that is used today to diagnose the disease. Also, new types of treatment focused on altering the gut microbiome of patients with PAH could be developed.

Another important question to be researched is how gut bacteria impacts the lungs of patients with PAH.

“We do not know if and how gut bacteria and viruses make their way to the lungs,” noted Dr. Raizada. “Some studies have pointed to an increased incidence in intestinal leakage among people with PAH, which may allow some intestinal bacteria to get into the bloodstream and circulate to the lungs where they can cause inflammation and lead to vascular changes.”

“There is still the question of whether the specific microbiota associated with PAH is the cause or the result of the disease, therefore, more research is needed,” he concluded.

Reference: https://www.ahajournals.org/doi/abs/10.1161/HYPERTENSIONAHA.119.14294

SOURCE: American Heart Association