Certain type of gut bacteria may help lower risk

By Staff 9 Min Read

  • Scientists have discovered that gut microbes play a significant role in influencing cardiovascular disease.
  • This builds upon previous research linking the gut microbiota to various health issues like diabetes and obesity.
  • Using data from the Framingham Heart Study, researchers identified specific bacteria in the gut that can break down cholesterol, suggesting a potential path to reducing heart disease risk.
  • This research not only sheds light on the mechanisms by which gut bacteria affect cholesterol levels but also opens the door for treatments aimed at modifying the gut microbiota to improve heart health.

Alterations in the gut microbiota have been linked to several illnesses, such as type 2 diabetes, obesity, and inflammatory bowel disease.

Researchers from the Broad Institute of MIT and Harvard in collaboration with Massachusetts General Hospital have recently discovered that gut microbes could also influence cardiovascular disease.

The new study, published in Cell, highlights particular bacterial species in the gut that digest cholesterol, potentially reducing cholesterol levels and the risk of heart disease in individuals.

The researchers examined metabolites and microbial genomes from over 1,400 participants in the long-running Framingham Heart Study, which investigates cardiovascular disease risk factors.

They found that a type of bacteria called Oscillibacter absorbs and processes cholesterol from its environment, noting that individuals with higher quantities of this microbe in their intestines exhibited reduced cholesterol levels.

The team also uncovered the process these bacteria likely employ to degrade cholesterol.

The findings imply that future interventions targeting the microbiota in specific manners may aid in lowering cholesterol levels in humans.

These discoveries provide a foundation for more focused research on the impact of microbiome alterations on health and disease.

Over the last decade, researchers have found associations between the makeup of the gut microbiota and aspects of cardiovascular disease, like levels of triglycerides and blood sugar after eating.

However, the development of treatments targeting these links has been challenging, mainly because of an incomplete understanding of the metabolic processes in the gut.

Now, researchers from the Broad Institute achieved a more thorough and detailed view of how gut microbes affect metabolism.

They used a powerful method called shotgun metagenomic sequencing to take a close look at all the DNA of the microorganisms within a sample.

Along with this, they applied a technique called metabolomics to measure the amounts of hundreds of known and even thousands of yet-to-be-identified substances produced by these organisms.

The method revealed over 16,000 links between microbes and metabolic characteristics, with one particularly notable finding: individuals hosting several species of bacteria from the Oscillibacter genus exhibited lower cholesterol levels compared to those without these bacteria.

Remarkably, Oscillibacter species were found to be quite prevalent in the gut, averaging about one in every 100 bacteria.

To understand how these microbes metabolize cholesterol, the researchers aimed to identify the biochemical pathway involved, which involved cultivating the organism in a laboratory setting.

Luckily, the laboratory had devoted years to collecting bacteria from stool samples, building a unique collection that includes Oscillibacter species.

After the researchers successfully cultivated the bacteria in the lab, they used mass spectrometry to pinpoint the likely byproducts created when the bacteria process cholesterol.

This helped them understand the methods these bacteria use to reduce cholesterol levels.

They discovered that the bacteria transform cholesterol into substances that other bacteria can further break down and the body can then eliminate.

By applying machine learning, the team identified specific enzymes that might be responsible for changing cholesterol into these substances.

In addition, the researchers identified another type of gut bacteria, Eubacterium coprostanoligenes, which also plays a role in lowering cholesterol.

This bacterium contains a gene known to be involved in processing cholesterol. In their latest findings, the team observed that Eubacterium may work together with Oscillibacter to further reduce cholesterol levels.

This indicates that future research focusing on how different types of bacteria interact could provide deeper insights into the complex ways the gut microbiota influences human health.

The researchers are aiming to understand how the complex world inside our guts works by starting with one tiny organism or gene at a time.

They believe this careful approach will help them figure out the system’s workings and create targeted treatments that could directly target harmful microbes.

Two experts, who were not involved in this research, spoke to Medical News Today about the study.

Cheng-Han Chen, MD, board certified interventional cardiologist and medical director of the Structural Heart Program at Memorial Care Saddleback Medical Center in Laguna Hills, CA, said, “the gut microbiome is increasingly being understood as playing a major role in human health, including cardiovascular health.”

“This study utilized metagenomic and metabolomic techniques to identify and focus on a specific species of gut bacteria (Oscillibacter) that appeared to be associated with lower stool and blood cholesterol levels, likely due to their cholesterol-metabolizing properties. As more research is performed to understand the connections between the microbiome and cardiovascular disease, we will be able to identify many more bacterial species that play a role in regulating our cardiovascular risk factors.”
— Dr. Cheng-Han Chen

Chen pointed out that “as gut uptake and metabolism of fats and cholesterol affects our blood cholesterol levels, it is important for us to understand the mechanisms by which this occurs.”

“This research can potentially lead to therapeutics that help our natural gut flora better maintain a favorable blood cholesterol profile, which in turn may even lead to improved cardiovascular health,” he explained.

Yu-Ming Ni, MD, board certified cardiologist and lipidologist at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA, agreed, saying, “there’s been a lot of interest in the effect of the microbiome on general health.”

“We coexist with trillions of organisms on our skin and in our intestinal and genitourinary tract. These organisms play a critical role in our ability to fight off external pathogens, in the metabolism of food, and in the health of our immune system. Specifically, this study shows that there are bacterial strains that may affect cholesterol exposure in the intestinal tract.”
— Dr. Yu-Ming Ni

“The discovery of the cholesterol metabolizing properties of Oscillibacter bacteria is fascinating, and it suggests the possibility of the use of this probiotic strain as a therapeutic agent for treating high cholesterol,” Ni said.

However, Ni also noted a few limitations of the study.

“Given that this study was in vitro, it is too early to tell whether the cholesterol effects of this organism in the human body can be replicated. More importantly, we don’t know what other effects this organism may have on the human body, and these other effects may be harmful,” he said.

Ni noted that “further study is needed in actual patients to determine if this organism can play a helpful role in reducing cholesterol uptake.”

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