Researchers at Sinai Health have uncovered evidence that the immune system may signal Crohn’s disease long before diagnosis — quietly, invisibly, and well ahead of clinical symptoms. A simple blood test, they suggest, may be able to identify this risk in otherwise healthy individuals.
The clue lies in how the immune system reacts to flagellin, a protein found on common gut bacteria. In a large, long-running cohort study of people with a family history of Crohn’s, elevated immune responses to this bacterial protein appeared years before disease onset. That timing challenges a long-held assumption: that immune dysfunction follows inflammation, rather than precedes it.
The findings raise bigger questions about what Crohn’s really is at its earliest stage — and whether the disease process begins not in symptoms, but in subtle immune misfires against the microbiome. If so, today’s treatment paradigm may be intervening far too late.
Why this matters for prevention, early diagnosis, and the future of IBD care — and how this work builds on one of the world’s most ambitious pre-disease cohorts — is where the full story unfolds.