Phage Therapy for inflammatory bowel disease (IBD)

Targeted phages curb Crohn's-linked gut inflammation by disabling harmful E. coli traits

Phage Therapy

Image credit: American Society for Microbiology

IBD affects millions, with rates continuing to rise, particularly among children. Although current treatments can be effective, they can fail long term or require escalating doses, increasing the risk of serious side effects.

A research team  has now developed a targeted approach to treating inflammatory bowel disease (IBD) using bacteriophages, viruses that infect specific bacteria, to disarm harmful microbes without disrupting the broader gut ecosystem.
Targeted bacteriophages directed against adherent-invasive E. coli reduced gut inflammation in experimental models of Crohn’s disease by suppressing virulence traits, particularly adhesion to intestinal cells, without eradicating the bacteria or disrupting the microbiota. Phage therapy also potentiated steroid efficacy, enabling lower doses, and stool-based functional assays may identify patients most likely to benefit.
IBD is shaped by a combination of genetics, immune responses and the gut microbiome. The research team focused on a group of bacteria known as adherent-invasive Escherichia coli (AIEC), which have been linked to inflammation in some people with Crohn's disease. These bacteria can be difficult to identify and selectively target, making them an important test case for more precise microbiome-based therapies.
Working with E. coli strains isolated from patients with Crohn's disease, the team used controlled experimental models to isolate how AIEC contribute to inflammation and explore ways to neutralize their harmful behaviour without damaging beneficial bacteria.
To target AIEC without collateral damage, the team turned to bacteriophages (phages), which are naturally occurring viruses that infect bacteria with remarkable precision.

Phages work like a lock-and-key system—each phage targets only certain bacteria. That precision gives us a way to intervene without wiping out the entire microbiome.

The team identified and characterized phages that selectively target AIEC strains isolated from patients with IBD and found that this approach significantly reduced gut inflammation.

The phages did not eliminate the bacteria entirely. Instead, they altered their behaviour by suppressing a molecular "grappling hook" that helps AIEC attach to the gut lining and trigger immune responses. When that virulence mechanism was turned off, inflammation subsided.

The bacteria were still there, but they lost the traits that drive inflammation as the bacteria can't do as much damage anymore.
The researchers also found that phage therapy enhanced the effectiveness of a commonly used steroid treatment for IBD. When combined with the phage, a lower-than-standard dose produced benefits comparable to higher doses of the drug alone. While phages have previously been shown to increase the effectiveness of antibiotics, this is the first time a positive collaboration between phage and a non-antibiotic drug has been reported.

The findings point to a precision-medicine approach for IBD.

Kyle Jackson et al, Phage intervention improves colitis and response to corticosteroids by attenuating virulence of Crohn's disease–associated bacteria, Science Translational Medicine (2026). DOI: 10.1126/scitranslmed.adz4589