Millions of people around the world have obstructive sleep apnea. Obstructive sleep apnea is a common disorder in which breathing is repeatedly interrupted during sleep. A new study in mice suggests that gut microbes and the compounds they produce may play a surprising role in protecting against some of the most serious conditions, including heart disease.
The findings, presented at ASM Microbe 2026, point to potential new targets for the prevention and treatment of cardiovascular complications associated with sleep apnea.
How sleep apnea syndrome affects the body
Obstructive sleep apnea causes a person to stop breathing repeatedly throughout the night. These interruptions reduce oxygen levels and increase carbon dioxide in the body, causing various harmful effects.
Previous research has shown that low oxygen levels can alter bile acids, substances produced in the liver, stored in the gallbladder, and released into the intestines to help digest fats. Beyond digestion, bile acids also act as chemical messengers that interact with receptors throughout the body.
Researchers have previously discovered that gut microbes can modify bile acids and influence the progression of atherosclerosis, or the amount of fatty plaque that builds up in the arteries, over time. Because bile acids enter the bloodstream, they can affect tissues and organs far beyond the digestive system.
“From previous research, we were pretty confident that bile acids, especially bile acids modified by microbes, were the key to controlling this disease. So we wanted to know what happens when one of the important receptors for bile acids is missing – does the disease go away?” said Celeste Allaband, DVM, Ph.D., first author of the study. Graduated from University of California, San Diego.
Testing for important bile acid receptors
To find out, the research team studied two groups of mice. One group consisted of mice genetically predisposed to heart disease, known as ApoE knockouts. The second group included mice that were also susceptible to heart disease but lacked a bile acid receptor called farnesoid X receptor (FXR). These animals are known as ApoE/FXR knockouts.
Both types of mice were exposed to either normal sleep conditions with room air or conditions designed to mimic sleep apnea. Throughout the study, the researchers analyzed fecal samples to track changes in gut bacteria and metabolites. At the end of the experiment, the animals were examined for plaque buildup in their arteries.
Reduces plaque and improves intestinal health
This result highlighted the important role of FXR in the development of cardiovascular disease in sleep apnea-like conditions.
“Our study shows that the FXR host receptor, which can be activated or inactivated by bile acids, plays a central role in promoting fatty plaque accumulation in arteries during conditions like sleep apnea,” Alaband said. “Surprisingly, removing this receptor from mice significantly reduced the development of arterial plaque in some areas and minimized disruption of the gut microbiome.”
Mice lacking the receptor developed significantly fewer plaques in the aorta and aortic arch, but some plaque remained in the pulmonary arteries. The researchers also observed that conditions like sleep apnea had a smaller impact on both the gut microbiome and metabolome in the absence of FXR.
“These results indicate that microbially modified bile acids and how they signal through the knockout receptor (FXR) appear to be key to the effects of sleep apnea-like conditions in the mouse model. We also identified specific bile acids to target for further investigation,” Alaband said.
Future sleep apnea treatment and probiotics
The research team is currently conducting several follow-up studies. One goal is to examine human datasets to determine whether similar patterns can be found in people with sleep apnea.
“We also plan to take some of the important bile acids and see if supplements of these compounds alone can help prevent or reduce disease,” Alaband said. “We can also take some key microorganisms that are important and see if we can administer them prophylactically as probiotics. There’s a lot of interesting research ahead.”
If translated to humans, this discovery could open the door to new treatments that target bile acid signaling and harness beneficial microbes to reduce cardiovascular risks associated with sleep apnea.
