Antimicrobial Antibody Response May Predict Crohn Disease Risk in First-Degree Relatives

TUESDAY, Jan. 13, 2026 (HealthDay News) -- For healthy first-degree relatives (FDRs) of patients with Crohn disease (CD), increased antibody response toward Lachnospiraceae flagellin is associated with the subsequent risk for CD, according to a study published online Jan. 11 in Clinical Gastroenterology and Hepatology.Richard Y. Wu, M.D., Ph.D., from the University of Toronto, and colleagues characterized the antimicrobial antibody responses before CD diagnosis in healthy FDRs of patients with CD. A total of 77 FDRs who later developed CD were matched by age, sex, follow-up duration, and geographic location with 304 healthy FDRs. Sera were probed for antimicrobial reactivity using a microbiota antigen microarray and a flagellin peptide cytometric bead array.The researchers found significant associations for 19 out of 49 immunoglobulin G (IgG) antimicrobial antibody responses with the risk for CD; these antibodies were reactive to the Lachnospiraceae family, especially Roseburia-derived flagellins. Positive correlations were seen for five antibodies with fecal calprotectin (FCP), while three were positively associated with lactulose-to-mannitol ratio (LMR). Significant amino acid sequence homology was shared by these IgG-seroreactive flagellins, characterized by a conserved "hinge peptide" within D0-D1 domains of the amino-terminus. Independent of LMR and FCP, elevated IgG seroreactivity to the hinge peptide was associated with the future risk for CD."We found that this immune response is driven by a conserved domain of the flagellin protein. This raises the potential for designing a flagellin-directed vaccine in selected high-risk individuals for prevention of disease. Further validation and mechanistic studies are underway," coauthor Sun-Ho Lee, M.D., also from the University of Toronto, said in a statement.Three authors disclosed ties to the biopharmaceutical industry.Abstract/Full Text (subscription or payment may be required).Sign up for our weekly HealthDay newsletter

Antimicrobial Antibody Response May Predict Crohn Disease Risk in First-Degree Relatives

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