In a development that should surprise absolutely no one who has ever felt the intimate connection between their stomach and their general will to live, researchers at Michigan Medicine have reversed a severe form of fatty liver disease in animal studies by targeting the gut. The experimental drug, DT-109, works by reducing harmful gut bacteria, protecting the intestinal lining, and preventing inflammatory substances from reaching the liver - proving once again that the liver is not an island, but rather the long-suffering roommate of your digestive tract.
According to findings published in The Journal of Clinical Investigation, this approach successfully reversed metabolic dysfunction-associated steatohepatitis (MASH) in animal models. MASH affects approximately 7% of the world's population and is a severe form of fatty liver disease where excess fat accumulates in the liver, causing inflammation and cellular damage. Over time, it can progress to cirrhosis, liver cancer, and liver failure. Treatment options have improved in recent years, but effective therapies remain limited - because of course they do.
"We see clear evidence that DT-109 protects the gut epithelial barrier, reducing the systemic influx of harmful microbial products that are thought to contribute to MASH development and progression," said Eugene Chen, M.D., Ph.D., senior author of the study and Frederick G. L. Huetwell Professor of Cardiovascular Medicine at the University of Michigan Medical School. "This compound shows benefits to the gastrointestinal system and has great potential as a treatment for MASH."
Chen's team had previously shown that DT-109, a glycine-based tripeptide (a small molecule made from three amino acids, the building blocks of proteins), could improve MASH in animal studies. What remained unclear was exactly how it worked. The latest research explains the mechanism, revealing how changes in gut bacteria set off a chain reaction that damages the liver - and how DT-109 interrupts it.
The scientists confirmed a key contributor to MASH: excessive growth of Clostridium perfringens, a bacterium that produces ammonia inside the intestines. When ammonia levels rise, they can damage the gut's protective inner lining. Normally, this barrier prevents harmful substances from escaping the digestive tract and entering the bloodstream. As the barrier weakens, toxins and microbial products travel to the liver, provoking inflammation and activating immune defenses in ways that worsen liver damage. One response involves excessive activation of CD8+ T cells, immune cells that normally destroy infected or abnormal cells but, when overactive, contribute to MASH inflammation. The findings help explain why a disease centered in the liver can be strongly influenced by events elsewhere in the digestive system - a concept that will shock anyone who has ever eaten a gas station burrito.
Through a series of experiments, researchers discovered that DT-109 disrupts this damaging cycle by improving the intestinal environment and reinforcing the gut's protective barrier. In both mice and nonhuman primates, the compound reduced levels of Clostridium perfringens and lowered ammonia production in the intestines. These changes strengthened the intestinal lining, limiting the movement of harmful microbial substances into the body and reducing their potential to damage the liver. The results were particularly encouraging in nonhuman primates, whose liver biology and gut microbial communities more closely resemble those of humans than mice do - a reminder that mice, while convenient, are not tiny furry people.
"DT-109 connects microbiota modulation with liver protection by restoring gut barrier integrity and limiting the systemic translocation of ammonia and other pro-inflammatory microbial products within the gut-liver axis," said Jifeng Zhang, Ph.D., co-author and research professor of cardiovascular medicine at U-M Medical School. "We also found that DT-109 primarily acts in the gastrointestinal tract, but its reach stretches much further."
The gut-liver axis refers to the close biological relationship between the digestive tract and the liver. Substances absorbed from the intestines travel to the liver through the bloodstream, making liver health particularly sensitive to changes in gut bacteria and intestinal barrier function. By targeting this connection, DT-109 may address some of the processes driving liver inflammation rather than focusing exclusively on damage that has already occurred - a novel concept in medicine, where treating the cause is often an afterthought.
Researchers believe the compound's ability to protect the intestinal barrier could make it useful against other conditions involving inflammation and metabolic dysfunction. Previous research has shown that DT-109 can reduce the formation of atherosclerotic plaques and prevent vascular calcification in nonhuman primates. Atherosclerotic plaques are deposits of fat and other substances that accumulate inside artery walls, potentially restricting blood flow and increasing the risk of cardiovascular problems. Vascular calcification occurs when calcium builds up in blood vessel walls, making them less flexible and contributing to cardiovascular disease. These findings suggest DT-109 could eventually have applications in treating both liver and cardiovascular conditions - an important possibility because metabolic disorders often affect multiple organs, much like a bad decision at a buffet.
The researchers are also interested in whether the compound could help people with inflammatory bowel disease (IBD), a group of chronic conditions that includes Crohn's disease and ulcerative colitis. Because problems with the intestinal barrier are associated with several gastrointestinal disorders, a treatment that strengthens this barrier might have benefits beyond protecting the liver. However, additional research will be needed to determine whether DT-109 is effective against these conditions - because science, annoyingly, requires evidence.
Despite the encouraging results, DT-109 remains an experimental treatment. Its ability to reverse MASH has been demonstrated in animal models, but researchers have not yet established whether it can safely and effectively produce similar benefits in humans. The next phase of research will involve further evaluation of the compound, with the goal of advancing it toward clinical trials. Those studies will be essential for determining its safety, appropriate use, and potential effectiveness in patients - a process that, unlike the drug's action, cannot be rushed.
"This study presents novel evidence about the pathogenesis of MASH and provides excitement about a therapeutic avenue to explore for a condition that remains difficult to treat," said Elliot Tapper, M.D., Academic Director of Hepatology at Michigan Medicine. "What patients with MASH need is a safe and effective therapy capable of improving their liver and heart health - of course we are excited about these developments."
The discovery highlights an important shift in how scientists are approaching fatty liver disease. By addressing harmful gut bacteria and restoring the intestinal barrier, researchers may be able to protect the liver through a treatment that acts primarily outside the organ itself. If future human studies confirm the benefits seen in animals, DT-109 could offer a new therapeutic option for patients with severe fatty liver disease while potentially addressing cardiovascular complications as well.
Ying Zhao, Oren Rom, Jifeng Zhang, and Y. Eugene Chen are listed as inventors on a patent application (Tripeptides and treatment of metabolic, cardiovascular, and inflammatory disorders). Chen is also an inventor of DT-109. The University of Michigan holds the patent for the compound and has licensed it to Diapin Therapeutics. Both Chen and the university have an ownership interest in Diapin, which supplied DT-109 for the research and is continuing its development - a disclosure that, while standard, always adds a certain frisson to the phrase "promising."
The human study protocol, all amendments, and the informed consent form received approval from the Institutional Review Boards at the participating sites. These included the First Affiliated Hospital of Xi'an Jiaotong University (approval number: XJTU1AF2023LSK330), the Institutional Review Board of Jinan University (approval number: 2016-017), and the University of Hong Kong/Hospital Authority Hong Kong West Cluster (approval number: UW 20-700). All experimental procedures involving nonhuman primates were approved by the Laboratory Animal Care Committee of Xi'an Jiaotong University (approval number: 20191278) and the Institutional Animal Care and Use Committee of Spring Biological Technology Development Co., Ltd. (approval number: 201901). The study was conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Materials provided by Michigan Medicine - University of Michigan. Note: Content may be edited for style and length.