Gut bacteria may have a protective effect

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The gut microbiome may influence heart health, research shows. Laura Herrera/Stocksy
  • Over the past few years, researchers have discovered more details on how the body’s gut microbiome affects its overall health.
  • An unhealthy gut microbiome, for example, has been linked to a variety of diseases.
  • Researchers from the University of Wisconsin–Madison have now identified specific bacteria in the gut microbiome capable of breaking down inflammation-causing uric acid— at least in mice.
  • Scientists believe this uric acid-eating bacteria could help protect the body from heart disease and gout.

Over the last few years, researchers have been uncovering more and more ways in which the body’s gut microbiome affects its overall health.

Previous research links an unhealthy gut microbiome to a variety of diseases, including type 2 diabetes, obesity, asthma, colorectal cancer, and neurodegenerative disorders like Parkinson’s disease.

Now, researchers from the University of Wisconsin–Madison have identified bacteria in the gut microbiome via a mouse model capable of breaking down inflammation-causing uric acid, helping to potentially protect the body from both heart disease and gout.

This study was recently published in the journal Cell Host & Microbe.

For this study, Dr. Federico Rey, associate professor of bacteriology at the University of Wisconsin–Madison and senior author of this study, and his team performed fecal transplants on mice. They transferred gut microbes from mature mice to mice born with microbe-free digestive tracts. This also caused the artery health of the mature mice to be expressed in the microbe-free mice.

Upon analysis, scientists found the mice who received microbes from donors with plaque-filled arteries and high levels of uric acid developed these same conditions. Similarly, mice who received microbes from donors with clearer blood vessels and less uric acid established the same features.

From there, the researchers were able to identify the specific microbes associated with health outcomes in the mice. Scientists were able to pinpoint a cluster of genes found across different types of bacteria needed to break down purines and uric acid in the intestine.

Researchers reported when the purine-lowering microbes used the uric acid in the intestines for their own needs, there was then less uric acid present in the blood of mice in the model.

“The findings from our study point to gut bacteria as potentially important contributors to uric acid levels,” Dr. Rey explained.

“These findings also have implications for understanding how microbes make a living in the gut. Our results show that uric acid is a [nutrient] — a source of carbon, energy, potentially nitrogen — for a lot of bacteria in conditions when there is no oxygen. We are interested in learning whether there are components of our diets that promote these organisms,” he added.

Uric acid is a waste product created when the body breaks down purines. Purines are naturally occurring chemical compounds in the body used to create DNA and RNA.

Additionally, purines can be found in high levels in certain foods and beverages, including seafood, red meat, game meats, organ meats, and both sweetened and alcoholic beverages.

When uric acid is produced, it is carried through the blood vessels to the kidneys where it is filtered out and leaves the body in urine.

If a person has too much uric acid in their bloodstream, it may not all leave the body, causing a build-up. A build-up of uric acid in the body is known as hyperuricemia.

“We have known for a long time that too much uric acid can cause gout. More recent studies have connected uric acid with other conditions, including metabolic and cardiovascular disease. Uric acid is a proinflammatory compound that can activate processes that exacerbate cardiovascular disease.”
— Dr. Federico Rey

With hyperuricemia, crystals of uric acid form causing inflammation in the body. These crystals can either get into the kidneys causing kidney stones. Or they can get into the body’s joints, causing a type of inflammatory arthritis known as gout.

And high levels of uric acid have also been linked to an increased risk for certain cardiovascular conditions, including high blood pressure and stroke.

This is not the first time the gut microbiome has been linked to heart disease. Previous research says the healthiness of gut microbiota has an impact on the development of cardiovascular disease in general.

Other studies have found a link between specific conditions, including coronary heart disease, stroke, hypertension, and atherosclerosis.

According to Dr. Rey, he and his team pursued this research as they were interested in learning more about how the gut microbiome impacts cardiovascular disease.

“In the context of these studies, we found associations between gut bacteria and uric acid levels and between this compound and markers of disease progression both in mice and humans. Others have observed associations between uric acid and cardiovascular disease,” he told Medical News Today.

“The unexpected finding was that uric acid variation was associated with gut bacteria,” Dr. Rey continued. “ By using animals grown in a highly controlled environment, we were able to show that gut microbes influence the abundance of uric acid in the host. This was a novel finding and motivated us to try to identify the bacteria and bacterial genes responsible for this effect.”

Dr. Rey said he thinks the idea of using gut bacteria or dietary interventions that promote specific bugs to help reduce uric acid for gout treatment or prevention is something that would be great to examine.

“At the same time, appropriate levels of uric acid and related compounds are necessary for host health, so the ultimate question is how gut microbes and diet interact and perhaps be manipulated to maintain levels of these compounds in a beneficial range — neither too high (nor) too low,” he added.

Dr. Rey also commented that the link with cardiovascular disease is less clear at this point, but it is something that we are interested in exploring.

“We still do not fully understand how gut bacterial metabolism influences uric acid in circulation,” he said when asked about the next steps for this research.

“This will be a priority in our group moving forward. We are also interested in testing the effect of bacterial modulation of uric acid on cardiovascular disease in preclinical models,” he added.

Medical News Today also spoke with Dr. Rigved Tadwalkar, a board certified cardiologist at Providence Saint John’s Health Center in Santa Monica, California, about this study.

He commented this was an interesting study because it gives clinicians more information on how gut health is related to cardiovascular health.

“We have seen now that elevated uric acid levels have been associated with the formation of arterial plaque and also the progression of atherosclerosis, which we characterize as an accumulation of those fatty deposits in the arteries,” he explained.

“What we know about the mechanism thus far is that uric acid can promote oxidative stresses, endothelial dysfunction, (and) inflammation, and each of these are key processes in the development of arterial plaque,” he said.

“What’s interesting about this study is seeing how specific bacteria might be capable of breaking down this uric acid, and how there is yet another link between gut microbiota and uric acid metabolism and, therefore, potentially for atherosclerosis. So having a deeper understanding of this is of high importance because it may help us come up with new or novel strategies for preventing or treating atherosclerosis.”
— Dr. Rigved Tadwalkar

When it comes to having a healthy gut microbiome, Dr. Tadwalkar said from a dietary standpoint, the best advice he can give somebody is to eat a diverse diet that includes a number of plant-based foods and stays away from processed and sugar-filled foods.

“Looking at the essential nutrients that provide or promote the growth of beneficial gut bacteria, those are found in fruits, vegetables, whole grains, and legumes — that’s where you get that rich array of nutrients that provide these microbial species for the gut,” he continued.

Dr. Tadwalkar also suggested watching for unnecessary antibiotic use, as antibiotics can disrupt the balance of the gut microbiome.

“And then from a lifestyle standpoint, stress management is important. There is some evidence that stress can disrupt the gut-brain axis. So obviously, stress-reducing activities would be highly encouraged — exercise, yoga, meditation, (and) things of that nature,” he added.

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