Gut Bacteria and Pulmonary Arterial Hypertension: An Unlikely Link

by Lauren Taylor from In The Cloud Copy

A variance in the amount or makeup of the bacteria in a person’s gut, called dysbiosis, could have strong implications for the onset and development of pulmonary arterial hypertension.

Pulmonary arterial hypertension or PAH is a condition of the blood pressure where the high pressures affect the ride side of the heart and the person’s arteries in their lungs. In PAH, the blood vessels in the lungs are blocked, destroyed, or narrowed, ultimately slowing down the flow of blood through the lungs, which causes the blood pressure in the lungs’ arteries to rise. This results in the heart having to work harder to pump the blood in and through the lungs, ultimately leading to the heart muscle becoming weak and possibly failing.

The exact causes of PAH are not always known but may include genetic mutations, use of certain drugs, including illegal drugs, congenital heart diseases, and other conditions such as lupus, HIV, and cirrhosis. There is currently no cure for PAH but it can be managed with medications and sometimes surgery, in severe cases.

The Key Role of Gut Bacteria

A study done on rat models may hold key information on the role of gut bacteria in the development of PAH. While the rat models in past studies did show that changes in the gut microbiome had PAH, it was still unknown if these changes in the microbiome of the gut were a result of the disease or the actual cause of the disease.

Researchers in Japan conducted a study by changing the composition of bacteria in the gut with a combination of antibiotics in rats that already had PAH. After administering the antibiotic combination, they observed if and how these changes affected the PAH parameters. Things they looked at included heart structure, blood pressure, and blood vessel structure.

The team injected the animals with SU5416, which is a protein inhibitor necessary for the development of the cells that line the lung blood vessels. This triggered the onset of PAH. During this time, they also administered some rats with an antibiotic cocktail in order to change their gut microbiome.

Researchers then collected stool samples from the rats to observe and identify the bacteria that was in the GI tracts of the animals. The PAH rats that were not given the antibiotic cocktail had notably increased firmicutes-to-bacteroidetes (F/B) ratios. The F/B ratio is frequently used as an indicator of dysbiosis.

Further research found that the rats in the induced PAH group that were given the antibiotics had significantly reduced numbers of bacteria in their GI tracts. Researchers also found that the PAH rats that received the antibiotic cocktail had reduced blood pressure of the right ventricle, which is the side that pumps blood into the lungs, compared to those rats with PAH that did not receive the antibiotic cocktail.

Additional findings included prevention of right ventricle enlargement in the group that received antibiotic treatment. The antibiotic cocktail also reduced narrowing of the blood vessels, as well as obstruction in the lungs.

Looking at all of these findings, researchers concluded that altering the gut bacteria composition with an antibiotic cocktail may halt PAH development and progression. Researchers believe these findings may present a new treatment option for those suffering from PAH.

Click here to see the original study.

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