Blood Test Revolutionizes Early Detection of Crohn’s Disease

Researchers at Sinai Health have developed a groundbreaking blood test that can predict Crohn’s disease years before any symptoms manifest. This innovative test measures an individual’s immune response to flagellin, a protein found in gut bacteria. The findings, led by Dr. Ken Croitoru, a clinician scientist at the Lunenfeld-Tanenbaum Research Institute, could pave the way for earlier diagnosis and potential prevention of this chronic inflammatory condition.

The research team, which also included gastrointestinal medical resident Dr. Richard Wu and clinician scientist Dr. Sun-Ho Lee, published their findings in the journal Clinical Gastroenterology and Hepatology. Their work highlights a significant connection between gut bacteria and the immune system’s response as a crucial factor in the development of Crohn’s disease.

Crohn’s disease impacts the gastrointestinal tract, leading to persistent digestive issues, pain, and fatigue. Its prevalence among children has doubled since 1995, and current estimates from Crohn’s and Colitis Canada suggest that approximately 470,000 Canadians will live with inflammatory bowel disease (IBD) by 2035.

The presence of antibodies against flagellin before symptoms appear indicates that this immune reaction may play a role in the onset of Crohn’s disease, rather than merely resulting from it. Dr. Croitoru emphasizes that understanding this early process could lead to new strategies for predicting, preventing, and treating the disease. He stated, “With all of the advanced biologic therapy we have today, patients’ responses are partial at best. We haven’t cured anybody yet, and we need to do better.”

This research is part of the Genetic, Environmental and Microbial (GEM) Project, which began in 2008. The project studies over 5,000 healthy first-degree relatives of Crohn’s disease patients, collecting genetic, biological, and environmental data to gain insights into disease development. So far, 130 participants have developed Crohn’s, providing a rare opportunity to study its earliest stages.

Previously, the team had discovered an inflammatory immune response targeting gut bacteria appears long before Crohn’s disease manifests. In healthy individuals, beneficial bacteria coexist in the gut, contributing to digestive health. In Crohn’s disease, the immune system mistakenly attacks these microbes.

Collaborators at the University of Alabama, led by Dr. Charles Elson, had previously established a test to detect antibodies against flagellin. They found that individuals with Crohn’s disease exhibit elevated antibody levels targeting flagellin from Lachnospiraceae bacteria. Drs. Croitoru and Lee aimed to determine if this immune response could also be detected in healthy individuals at risk for developing the disease.

In their study, the team analyzed 381 first-degree relatives of Crohn’s patients, finding that 77 went on to develop the disease. Among these, 28 individuals—more than a third—showed elevated antibody responses, particularly among siblings, indicating the influence of shared environmental factors.

The researchers confirmed that this pre-disease immune response to the flagellin was linked to intestinal inflammation and gut barrier dysfunction, both indicative of Crohn’s disease. The typical timeline from blood sample collection to diagnosis for these pre-disease individuals was nearly two and a half years.

“Confirming our previous study, the immune response against bacterial flagellins shows strong associations with future risk of Crohn’s in healthy first-degree relatives,” said Dr. Lee. He added that the immune response is driven by a conserved domain of the flagellin protein, which raises potential for designing a flagellin-directed vaccine for high-risk individuals to prevent the disease. Further validation and mechanistic studies are currently in progress.

The implications of this research are profound, as it not only enhances understanding of Crohn’s disease but also offers hope for future preventative measures. The work of Dr. Croitoru and his team represents a significant step forward in the quest to mitigate the impact of this challenging condition.