A fiber-derived bacterial metabolite may leave a protective memory in the gut lining that supports long-term immune tolerance.
A signal made by gut bacteria as they break down dietary fiber may continue shaping intestinal immunity long after the signal itself disappears. Northwestern Medicine researchers found that butyrate can leave a durable molecular imprint on the cells lining the intestine, encouraging immune tolerance and protecting mice against conditions resembling inflammatory bowel disease after treatment has ended.
The findings were published in Nature Communications. Yingzi Cong, PhD, the Stanley Gradowski Professor of Gastroenterology and a professor of Microbiology-Immunology and of Pathology, served as senior and co-corresponding author.
The results suggest that beneficial compounds produced by gut microbes may effectively “train” the intestinal lining to preserve an immune-regulating state over time.
“Our laboratory has long been interested in how the gut microbiota regulates immune responses at intestinal mucosal surfaces,” said first and co-corresponding author of the study Tianming Yu, PhD, research assistant professor of Medicine in the Division of Gastroenterology and Hepatology. “Short-chain fatty acids (SCFAs), which are produced by gut bacteria during the fermentation of dietary fiber, are known to have anti-inflammatory effects in the intestine.”
One important question, however, had remained unresolved.
“A large proportion of butyrate in the gut is rapidly absorbed and metabolized by intestinal epithelial cells (IECs), which limits the amount of free butyrate that can directly reach underlying immune cells,” Yu said. “This led us to ask whether butyrate might act through IECs to regulate intestinal immunity.”
Butyrate leaves lasting immune protection
To investigate that possibility, the researchers added butyrate to the drinking water of mice for a set period and then withdrew it. Two weeks after treatment stopped, CD4+ T-cells were still producing elevated levels of IL-10, a major anti-inflammatory cytokine that helps control inflammation in the intestine.
The treated mice were also more resistant to chemically induced colitis. Compared with untreated animals, they lost less weight, had lower levels of inflammatory markers, and developed less severe tissue damage. The study found that this protection depended on IL-10 signaling.
Changes in the existing gut microbial community did not explain the result. When the experiment was repeated in germ-free mice, which have no microbes, butyrate still produced a lasting immune-regulating environment.
“We found that oral butyrate treatment induces a sustained immunoregulatory response in the intestine, characterized by increased IL-10 production in CD4+ T-cells and protection from intestinal inflammation even after butyrate treatment is stopped,” Yu said. “This effect was also observed in germ-free mice, suggesting that butyrate can establish a lasting intestinal environment that does not depend on continuous microbial stimulation.”
Intestinal cells carry the signal
Yu and his collaborators next examined intestinal epithelial cells (IECs), the cells that create the physical boundary between the body and the gut microbiome. In laboratory experiments, epithelial cells previously exposed to butyrate strongly increased IL-10 production in both mouse and human T-cells.
“We further found that conditioned medium from butyrate-treated IECs strongly induced IL-10-producing CD4+ T-cells in both mouse and human T-cell culture systems,” Yu said. “These findings suggest that IECs secrete some immunoregulatory factors after butyrate treatment, and these factors can act on T-cells.”
A metabolite connects cells to tolerance
Metabolomic analysis, which measures small molecules produced during cellular activity, identified N1-acetylspermidine as one likely messenger. The compound increased IL-10 production in T-cells and appeared to account for part of the immune-regulating effect produced by butyrate-treated epithelial cells, Yu said.
“Mechanistically, we found that butyrate acts on IECs and induces sustained transcriptional and epigenetic activation of Sat1, an acetylpolyamine biosynthetic enzyme,” Yu said. “This promotes production of the metabolite N1-acetylspermidine, which contributes to the ability of butyrate-treated IEC-conditioned medium to induce IL-10 production in CD4⁺ T-cells.”
The results challenge the conventional view that intestinal epithelial cells are temporary responders whose main function is to form a protective barrier.
“The significance of this work is that it identifies a mechanism by which a microbiota-derived metabolite can create durable epithelial T-cell crosstalk,” Yu said. “The intestinal epithelium is often viewed as a short-lived barrier that responds rapidly to luminal stimuli. Our findings suggest that it can also retain a lasting imprint of a microbial metabolite signal. The study also introduces the idea that beneficial microbial metabolites may ‘train’ the IECs to maintain immune tolerance over time.”
Human disease remains the next test
The findings still require further confirmation, but Yu said the pathway could eventually prove relevant to inflammatory bowel disease.
“One important next step is to determine how this epithelial metabolic pathway operates in human intestinal disease, especially in patients with inflammatory bowel disease,” Yu said. “We are interested in testing whether the butyrate-Sat1-N1-acetylspermidine pathway is altered in human IECs and whether it correlates with immune regulation or disease activity.”
The researchers also intend to identify other metabolites involved in the response because N1-acetylspermidine did not fully account for the immune-regulating effects they observed.
More broadly, the findings may change how researchers think about the relationship among diet, microbial metabolites and the intestinal lining.
“Many studies have focused on how inflammation can leave harmful memory in epithelial cells, but our findings suggest that beneficial microbial metabolites may also establish protective epithelial programs,” he said. “Understanding how diet, microbiota-derived metabolites and inflammation shape intestinal epithelial memory could open new directions for restoring intestinal immune tolerance in inflammatory bowel disease.”
Reference: “Butyrate epigenetically licenses sustained epithelial-T cell crosstalk for intestinal immune tolerance” by Tianming Yu, Wenjing Yang, Anthony J. Bilotta, Suxia Yao, Jeong-Heon Lee, Qihong Zhao, Jia Zhou, Tamas Ordog, Parambir S. Dulai and Yingzi Cong, 15 July 2026, Nature Communications.
DOI: 10.1038/s41467-026-75600-w
The study was supported by National Institutes of Health grants DK135193, DK124132 and DK145439.
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