The optical tool, known as a luminescent reporter, lights up when it detects the molecule, with higher readouts indicating increased activity and inflammation.
The new technique could boost the accuracy of stool sample tests for IBD, reducing the need for invasive, expensive procedures, experts say.
IBD is a chronic illness where the body’s immune system mistakenly attacks the digestive tract, leading to long-lasting inflammation. Diagnosis and monitoring of the condition often rely on colonoscopies, where a small camera is used to examine the gut.
Current IBD stool tests measure general markers of inflammation, such as the protein calprotectin, so a positive result requires further investigation to confirm the source.
University of Edinburgh researchers studied gut tissue from IBD patients and identified high levels of an enzyme – a molecule that speeds up chemical reactions in cells – called granzyme A (GzmA) in inflamed gut tissue compared with non-inflamed tissues.
GzmA is released by T cells – a type of white blood cell – which usually protect the body by finding and fighting infections or abnormal cells. In IBD, T cells mistakenly see the gut as a threat and become overactive, which can lead to tissue damage and inflammation.
The research team developed a luminescent reporter to measure the activity of GzmA in stool samples. The reporter tool was tested on 150 samples from both IBD and healthy patients.
Combining the new reporting tool with the current common testing of faecal calprotectin levels was more successful in identifying IBD in patients than using faecal calprotectin scores alone.
Researchers say the ability to identify gut-specific inflammation is a step forward for IBD diagnosis, but caution further research is needed before it can be used in a clinical setting.
The tool will form part of the assets of a new company in the process of spinning out of the University of Edinburgh, called IDXSense, supported by Edinburgh Innovations, the University’s commercialisation service.
The technique could also support the development of personalised IBD treatments in the future, with the ability to rapidly and accurately monitor gut inflammation levels in response to different therapies, experts say.
Reference:
Scott, J.I., Cheng, Z., Thompson, E.J. et al. A chemiluminescence assay targeting granzyme A activity for monitoring inflammatory bowel disease. Nat. Biomed. Eng (2026). https://doi.org/10.1038/s41551-025-01588-1
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