Imagine living with a condition where your gut is constantly under attack, leading to painful, tunnel-like structures that burrow into surrounding tissues—a reality for nearly 30% of people with Crohn's disease. But what if we could stop these devastating fistulas before they even form? Scientists at the University of Oxford have taken a monumental step toward this goal by uncovering the hidden culprits behind Crohn's fistulas. And this is the part most people miss: it’s not just inflammation, but a rogue group of cells behaving like they’re in a fetal gut, long after they should have grown up.
Crohn's disease, a chronic condition affecting roughly 1 in 650 people, causes parts of the digestive tract to become swollen, inflamed, and ulcerated. When these ulcers fail to heal properly, fistulas can develop, creating painful tunnels that sometimes connect the gut to other organs or even the skin. Until now, the exact mechanisms driving their formation and persistence have remained a mystery, making treatment incredibly challenging.
In a groundbreaking study published in Nature (https://www.nature.com/articles/s41586-025-09744-y), researchers analyzed thousands of individual cells from Crohn's fistulas, comparing them to healthy gut tissue. Using cutting-edge single-cell and spatial analysis techniques, the team at the MRC Weatherall Institute of Molecular Medicine (https://www.imm.ox.ac.uk/) mapped the intricate composition and behavior of cells within these fistula tracts. But here's where it gets controversial: they discovered that fistulas are lined with concentric rings of fibroblasts—cells typically responsible for maintaining tissue structure—that have been reprogrammed to act like cells from early fetal gut development. This out-of-context behavior is both fascinating and destructive.
These 'rogue' fibroblasts erode surrounding tissue near the tract surface, promoting tunneling, while deeper fibroblasts produce stiff, fibrotic material that stabilizes the tunnels. As Dr. Agne Antanaviciute (https://www.imm.ox.ac.uk/people/agne-antanaviciute), one of the senior authors, explains, 'These fibroblasts have essentially reactivated developmental programs that should only be active before birth. This reawakening makes them highly destructive, driving both tissue erosion and tunnel persistence.'
Even more intriguing, traces of these abnormal fibroblasts were found in small numbers at the bases of ulcers in Crohn's patients who hadn’t yet developed fistulas. This suggests that early intervention could potentially prevent fistulas from forming altogether. But is it ethical to intervene at such an early stage, and what are the long-term implications?
Professor Alison Simmons (https://www.rdm.ox.ac.uk/people/alison-simmons), senior author and Director of the MRC Translational Immune Discovery Unit (https://www.imm.ox.ac.uk/research/units-and-centres/mrc-translational-immune-discovery-unit), highlights the limitations of current Crohn's treatments, which focus on suppressing inflammation but do little to promote tissue repair. 'By identifying the cell types and pathways driving fistula formation, we now have the vital information needed to design and test preventive measures and novel wound-healing approaches,' she said.
The Oxford team's work has produced the largest dataset of its kind, integrating single-cell, spatial, and molecular imaging data across diverse patient samples. All data have been made publicly available to accelerate global research into Crohn's complications. This opens the door for drug discovery aimed at restoring healthy cell communication and wound healing within the gut—a critical step toward therapies that could prevent or reverse one of Crohn's most devastating complications.
Clinical researcher Colleen McGregor (https://www.rdm.ox.ac.uk/people/colleen-mcgregor), co-first author of the study, shared her enthusiasm: 'As someone who sees the burden of this complication firsthand, I’m thrilled to have helped define key aspects of fistula biology, an area where data have long been limited. This work showcases the power of interdisciplinary collaboration between clinical medicine and science—the cornerstone of high-quality IBD care.'
The paper, Spatial Fibroblast Niches Defining Crohn's Fistulae (https://www.nature.com/articles/s41586-025-09744-y), is published in Nature (https://www.nature.com/articles/s41586-025-09744-y). The research was supported by the UKRI Medical Research Council (MRC) (https://www.ukri.org/councils/mrc/), the Leona M. and Harry B. Helmsley Charitable Trust (https://helmsleytrust.org/), the National Institute for Health and Care Research (NIHR) Oxford Biomedical Research Centre (https://oxfordbrc.nihr.ac.uk/), and the Wellcome Trust (https://wellcome.org/).
What do you think? Is early intervention the key to preventing Crohn's fistulas, or are we opening a Pandora's box of ethical and medical challenges? Share your thoughts in the comments below!
