Crohn's Disease Patients Uniquely Contain Inflammatory Responses to Flagellin in a CD4 Effector Memory Subset

Nadine N. Morgan, Lennard W. Duck, Jiongru Wu, Mahmud Rujani, Paul G. Thomes, Charles O. Elson, Peter J. Mannon

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Background: Specific microbial antigens stimulate production of antibodies indicative of the aberrant immune response in Crohn's disease (CD). We tested for T cell reactivity linkage to B cell responses and now report on the prevalence, functionality, and phenotypic differences of flagellin-specific T cells among CD patients, ulcerative colitis (UC) patients, and control subjects and association with clinical features and flagellin seropositivity within CD patients. Methods: Sera from non-inflammatory bowel disease control subjects, CD patients, and UC patients were probed for antibody reactivity to gut bacterial recombinant flagellin antigens. Peripheral blood mononuclear cells were measured for flagellin antigen (CBir1, A4 Fla2, FlaX) or control (Candida albicans, and CytoStim) reactivity analyzed by flow cytometry for CD154 and cytokine expression on CD4+ T cells. Supernatants from post-flagellin-stimulated and unstimulated cells were used to measure effects on epithelial barrier function. Results: CD patients had a significantly higher percentage of flagellin-specific CD154+ CD4+ cells that have an effector memory T helper 1 and T helper 17 phenotype compared with UC patients and healthy control subjects. There was a positive correlation between the frequency of flagellin-specific CD154+ CD4+ effector memory T cells and serum levels of anti-flagellin immunoglobulin G in the CD patients. In addition, A4 Fla2-reactive T cells from active CD patients produced cytokines that can decrease barrier function in a gut epithelium. Conclusions: These findings demonstrate a Crohn's-associated flagellin-reactive CD4 cell subset distinct from UC patients and control subjects. There is a link between these cells and flagellin seropositivity. This CD4 cell subset could reflect a particular endophenotype of CD, leading to novel insight into its pathology and treatment.

Original languageEnglish (US)
Pages (from-to)1893-1903
Number of pages11
JournalInflammatory Bowel Diseases
Issue number12
StatePublished - Dec 1 2022


  • barrier dysfunction
  • cytokines
  • effector memory CD4 T cells
  • flagellin antigen

ASJC Scopus subject areas

  • Immunology and Allergy
  • Gastroenterology


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