Chronic inflammation in the gut does more than cause pain and discomfort for people with inflammatory bowel disease. A growing body of research suggests that prolonged inflammation can reshape the cellular and microbial environment of the colon in ways that may favor cancer development over time. Scientists at Weill Cornell Medicine and other institutions have reported molecular pathways that link persistent gut inflammation with the recruitment of immune cells implicated in tumor formation, shifts in bacterial populations, and longer-lasting changes to how DNA is packaged in colon-lining stem cells.
How IBD Recruits Cancer-Friendly Immune Cells
Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, is defined by long-lasting inflammation that damages the intestinal lining through repeated cycles of injury and repair. What makes this especially dangerous is not just the tissue damage itself but the way it reprograms the immune system. Neutrophils, a type of white blood cell normally deployed to fight infection, have been reported to promote colorectal tumor formation in some experimental settings, in part by releasing reactive molecules that can damage DNA and alter the local tissue environment.
In a study published in Immunity (DOI: 10.1016/j.immuni.2025.12.008), researchers mapped a signaling chain they linked to these inflammation-driven neutrophil changes. The authors described a TL1A-to-ILC3-to-GM-CSF axis that, in their model, increased neutrophil production in the bone marrow, recruited neutrophils into the inflamed colon, and shifted them toward a tumor-associated neutrophil gene signature. The experiments used a well-established mouse model of colitis-associated tumorigenesis, combining the carcinogen AOM with the inflammatory agent DSS to simulate the progression from chronic inflammation to cancer.
Separate work published in Cellular and Molecular Immunology provided corroborating evidence that TL1A, especially when combined with the cytokine IL-18, can elevate GM-CSF and enhance granulopoiesis in a broader immune context. This means the neutrophil-boosting effect is not limited to the gut wall but operates as a systemic alarm that floods the body with immune cells primed for a role that, in the context of chronic disease, turns harmful.
Inflammation Reshapes the Microbiome Toward Danger
The immune cell story is only one side of the equation. Chronic inflammation also changes which bacteria thrive in the gut, and those changes carry their own cancer risk. In colitis-susceptible mice, inflammation was shown to reshape microbial composition and select for genotoxic bacteria, particularly strains of E. coli carrying the pks gene cluster. These pks-positive E. coli produce a toxin called colibactin that can damage host DNA, and they have been associated with colorectal tumorigenesis in prior research.
More recent biomarker research has identified specific bacterial families that shift in predictable ways during inflammation and cancer. Enterobacteriaceae, the family that includes E. coli, tends to increase, while beneficial Bifidobacteria decline. These patterns have emerged as potential biomarkers for organ dysfunction and malignant transformation. The practical implication is that a simple microbial profile could one day help clinicians identify which IBD patients face the highest cancer risk, though no validated clinical test exists yet.
What makes this microbial shift especially concerning is that it may not be random. Studies in animal models suggest inflammation can select for bacteria that contribute to further damage, creating a potential feedback loop. In that context, an inflamed gut may become more hospitable to genotoxic species, which could increase DNA damage linked to cancer development.
Stem Cells Remember Past Inflammation
Even when inflammation subsides, the colon may not fully recover. Research available via the National Library of Medicine has reported that repeated cycles of inflammation, damage, and healing can encode a heritable epigenetic “memory” in colonic stem cells. This memory involves persistent changes in chromatin accessibility, notably at AP-1 transcription factor binding sites, that lower the threshold for tumor formation and promote malignant outgrowth once the right mutations occur.
A separate study published in Developmental Cell confirmed that intestinal stem cells can stably propagate inflammatory states through persistent chromatin accessibility changes, a phenomenon the authors described as cell-intrinsic inflammatory memory. Using mouse intestinal epithelium and organoid cultures, the team tied this memory to IFN-gamma and STAT1 signaling. In plain terms, the stem cells that regenerate the gut lining after each bout of inflammation carry forward a molecular record of that inflammation, and that record makes them more susceptible to becoming cancerous.
These findings raise questions about a common assumption in IBD management: that controlling active inflammation is sufficient on its own to reduce cancer risk. If stem cells retain a pro-inflammatory and pro-tumorigenic epigenetic state even during remission, then the window of cancer vulnerability may extend well beyond periods of active disease. Screening guidelines are typically based on clinical history and markers of disease activity rather than measures of “cellular memory,” which could mean some patients in clinical remission may still carry elevated risk.
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*This article was researched with the help of AI, with human editors creating the final content.
