Researchers investigating gut microbiota in cases of pulmonary arterial hypertension (PAH) discovered that several bacterial species were associated with disease severity, supporting calls for further investigation into their role in driving PAH pathology, according to a study published in Pulmonary Circulation.

PAH is characterized by right heart failure and death in later stages. There are a number of systemic physiological and biochemical changes that have been linked to PAH-associated right heart failure. One theory proposes that alterations in the gut microbiome are responsible in part for driving the conditions that lead to right heart failure. 

“Abnormalities in the composition of the intestinal microbiome have also recently been described in human PAH, but have yet to be validated or studied in a comprehensive fashion,” Jose and colleagues wrote. They thus decided to investigate intestinal microbiome composition in patients with PAH in the hopes that the information may be useful for developing future therapies.

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The research team recruited 20 patients with PAH who were clinically stable (deemed to not have changed their medication regime in the past 3 months). A total of 20 control subjects without PAH were also recruited. Participants were asked to provide stool samples using a stool collection kit. The researchers then extracted fecal DNA for sequencing. 

The results demonstrated no differences across various measures of microbial abundance and diversity between the PAH group and the control. There was, however, a relative increase in the abundance of Anaerostipes rhamnosivorans and a relative deficiency in Amedibacterium Intestinale, Ruminococcus albus, and Ruminococcus bicirculans in patients with PAH with more severe disease. In addition, there was a relative deficiency in Lachnospiraceae bacterium GAM79 in the PAH group compared to the control.

“Our results support further investigation into the complex relationship between the intestinal microbiome and circulating metabolite levels in PAH,” Jose et al concluded.


Jose A, Apewokin S, Hussein WE, Ollberding NJ, Elwing JM, Haslam DB. A unique gut microbiota signature in pulmonary arterial hypertension (PAH): a pilot study. Pulm Circ. Published online February 11, 2022. doi:10.1002/pul2.12051