Gut bacteria may increase stroke risk and reduce function after stroke


New findings from Cleveland Clinic researchers show for the first time that the gut microbiome impacts stroke severity and functional impairment after stroke. The results of the study, published in Cell Host & Microbe, lay the groundwork for a potential new approach to help treat or prevent stroke.

The study, led by Drs Weifei Zhu and Stanley Hazen, of the Cleveland Clinic’s Lerner Research Institute looked at the role of the gut microbiome in cardiovascular health and disease. In addition, they studied the adverse effects of TMAO (trimethylamine N-oxide), a by-product produced when gut bacteria digest certain nutrients found in red meat and dairy products. other animals.

New research shows that gut microbiota impacts stroke severity and functional decline after stroke. (Illustrated image)

“In this study, we found dietary choline and TMAO,” said Dr. Hazen, chair of the Department of Cardiovascular & Metabolic Sciences and director of the Cleveland Clinic’s Center for Microbiology & Human Health. drinking produced greater stroke size and severity and poorer outcomes in animal models.

Notably, simply transplanting gut bacteria capable of producing TMAO was enough to induce a large change in stroke severity.”

Previously, Dr. Hazen and his team found that elevated levels of TMAO can lead to the development of cardiovascular disease. In clinical studies with thousands of patients, they have shown that blood levels of TMAO predict future risk of heart attack, stroke, and death. The same previous studies, also by Drs Zhu and Hazen, were the first to show a link between TMAO and an increased risk of blood clots.

Dr Hazen said: “The new study expands on these findings and provides for the first time evidence that gut bacteria in general – specifically TMAO can have a direct impact on severity. severity of stroke or functional impairment after stroke”.

Diets high in red meat are thought to increase the number of gut bacteria that have an impact on stroke risk and impaired function after stroke. (Illustrated image)

The researchers compared brain damage in preclinical stroke models between people with increased or decreased levels of TMAO. Over time, people with higher levels of TMAO experienced more brain damage and a greater degree of motor and cognitive impairment after stroke.

They also found that changes in diet that alter TMAO levels, such as eating less red meat and eggs, affect stroke severity. “Post-stroke function, which occurs when blood flow to the brain is blocked, is of great interest to patients. To understand whether choline and TMAO affect function after stroke, beyond severity of stroke, we compared performance on different tasks before stroke, over both short-term and long-term post-stroke,” said Dr. Hazen.

The team found that a gut bacterial enzyme important for TMAO production called CutC increased the severity of stroke and made the condition worse. According to Dr. Zhu, targeting this gut bacterial enzyme could be a promising approach to stroke prevention.

“When we genetically silenced the gut bacteria gene that encodes CutC, stroke severity was significantly reduced. Ongoing studies are exploring this treatment, as well as the potential of dietary interventions to reduce TMAO levels and stroke risk. Western diets and diets rich in red meat both increase TMAO levels. Therefore, changing to a plant-based protein diet will help reduce TMAO,” she said.

Huong Giang (via: Science Daily)

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