Link Between Gut Microbes and Sleep Apnea Discovered

Summary: A new study has identified a novel therapeutic target to prevent life-threatening heart and metabolic complications in patients with obstructive sleep apnea. The research demonstrates how gut microbes modify bile acids to regulate physiological disease pathways.

Using gene-targeted mouse models, investigators revealed that knocking out a specific bile acid sensor, the farnesoid X receptor (FXR), significantly lowers the accumulation of fatty arterial plaques and stabilizes the gut microbiome under sleep apnea conditions.

Key Facts

The Sleep Apnea Hypoxia Factor: Obstructive sleep apnea causes repeated nightly breathing interruptions, depriving tissues of oxygen while raising carbon dioxide levels. This chronic oxygen deprivation alters bile acids, turning them into pathological chemical messengers throughout the bloodstream.
The FXR Driver Unmasked: Researchers demonstrated that the host FXR receptor, which is activated or deactivated by circulating bile acids, plays a primary role in driving the buildup of fatty plaques (atherosclerosis) in the arteries during sleep apnea.
The Genetic Knock-Out Assay: To isolate the role of this pathway, lead author Dr. Celeste Allaband compared two distinct mouse models: standard heart disease-prone mice (ApoE knock-outs) and mice lacking both the disease protection and the bile receptor (ApoE/FXR knock-outs).
Significant Reduction in Arterial Plaques: When exposed to simulated sleep apnea conditions, mice lacking the FXR receptor showed a severe drop in the development of fatty plaques within critical vascular zones, specifically the aorta and the aortic arch.
Microbiome and Metabolome Stabilization: Beyond shielding the cardiac infrastructure, removing the FXR receptor minimized disruptions to the gut microbiome and protected the metabolic profile in fecal samples from sleep apnea-driven decay.
Pulmonary Artery Exception: While plaque accumulation was mitigated across major systemic arterial lines, investigators noted that fatty plaques were still present on the pulmonary artery, indicating a localized difference in vascular disease mechanics.
Future Probiotic and Supplement Pipeline: The UCSD team plans to cross-reference these findings with human clinical datasets, while launching follow-up trials to test whether targeted probiotic microbes or specific bile acid supplements can be administered preventively to lower heart disease risk.

Source: American Society of Microbiology

Studies in mice reveal a new target for potentially treating and preventing life-threatening cardiovascular complications in the millions of patients with sleep apnea worldwide.

The study, presented at ASM Microbe 2026, showed how microbes modify bile to help protect mice from sleep apnea’s heart and metabolic toll.

This shows a brain on pillows. — Knocking out the farnesoid X receptor (FXR) significantly reduces fatty plaque accumulation in the aorta and stabilizes the gut metabolome during sleep apnea conditions. Credit: Neuroscience News

Obstructive sleep apnea is a widespread sleep disorder where a person’s breathing repeatedly stops and starts throughout the night. This deprives the body of oxygen and builds up carbon dioxide, causing a variety of issues in the body.

Previous research has shown that the lack of oxygen alters bile acids, which are compounds made by the liver, stored in the gallbladder and released in the intestines to digest fats. However, bile acids also act as chemical messengers to different receptors in the body.

In previous papers, the researchers showed that bile acids can be modified by microbes and affect how much of the fatty plaques on the heart (atherosclerosis) are present at the end of the study. Since bile acids are absorbed into the bloodstream, they can bind to receptors all over the body and cause changes in physiology.

“We were pretty sure from our previous studies that bile acids, especially microbially modified ones, were a key to regulating the disease so we wanted to know what happens when one of the key receptors for them are missing — does the disease go away?” said study first author Celeste Allaband, DVM, Ph.D. from the University of California, San Diego.

Allaband explained that there were 2 types of mice in the study: those prone to heart disease (called ApoE knock-outs) and those prone to heart disease that also have a particular bile acid receptor missing —the farnesoid X receptor (FXR) (these mice are called ApoE/FXR knock-outs).

The researchers exposed both types of mice to both normal room air sleeping conditions or sleep apnea-like sleeping conditions. Then the researchers looked at the microbes and metabolites in the gut (via fecal samples) during the study as well as the fatty plaques on the heart at the end of the study.

“Our study shows that the FXR host receptor, which can be activated or deactivated by bile acids, plays a central role in driving the buildup of fatty plaques in the arteries during sleep apnea-like conditions,” Allaband said. “Strikingly, when this receptor was removed from the mice, the development of arterial plaques dropped significantly in some areas and disruptions to the gut microbiome were minimized.”

The researchers found that knocking out the bile acid receptor resulted in significantly fewer fatty plaques in both the aorta and aortic arch, but there were still some present on the pulmonary artery. They also saw reduced impact of sleep apnea-like conditions on the gut microbiome and metabolome.

“These results tell us that microbially modified bile acids and how they signal through the receptor we knocked out (FXR) seem to be key to the impact of sleep apnea-like conditions in our mouse model. We also identified specific bile acids of interest to explore further,” Allaband said.

The researchers are exploring several different avenues to follow up on these results, including checking human datasets to see if they can see similar trends.

“We also plan to take some of our key bile acids of interest and see if supplementation of these compounds alone can help prevent or reduce disease,” Allaband said. “We may also take some key microbes of interest and see if they can be given preventively as a probiotic. There is lots of exciting future work to come.”

Key Questions Answered:

Q: How can a chemical made in the liver to digest fat affect whether someone has a heart attack caused by sleep apnea?

A: Because bile acids double as systemic chemical messengers. When sleep apnea deprives the body of oxygen, it alters these bile acids, which then travel through the bloodstream and bind to receptors all over the cardiovascular system, triggering the accumulation of fatty plaques in the arteries.

Q: What happened to the arteries of mice when scientists completely removed the FXR bile receptor?

A: The development of dangerous arterial plaques dropped significantly. By removing the FXR receptor, the altered bile acids had no way to transmit their destructive signals, resulting in far fewer fatty plaques in both the aorta and aortic arch while protecting the gut microbiome.

Q: Does knocking out this specific bile receptor protect every single blood vessel in the body from sleep apnea damage?

A: No, the protection is localized. While removing the FXR receptor successfully shielded the aorta and the aortic arch, researchers found that fatty plaques were still present on the pulmonary artery, showing that sleep apnea impacts different blood vessels through separate biological pathways.