Abnormal CEACAM6 expression in Crohn disease patients favors gut colonization and inflammation by adherent-invasive E. coli.

Abnormal expression of CEACAM6 is observed at the apical surface of the ileal epithelium in Crohn's disease (CD) patients, and CD ileal lesions are colonized by pathogenic adherent-invasive Escherichia coli (AIEC). The paper of Carvalho et al. recently reported that CD associated AIEC colonize and induce strong gut inflammation in transgenic mice expressing human CEACAM6 acting as a receptor for type 1 pili produced by AIEC bacteria. AIEC also induce CEACAM6 expression by intestinal epithelial cells directly by adhering to host cells and indirectly via increased secretion of TNF-α from AIEC-infected macrophages. Patients expressing a basal level of CEACAM6 in ileum could be predisposed to develop ileal CD and blocking interaction between type 1 pili and CEACAM6 might serve as a specific means of disrupting the colonization and the subsequent inflammatory amplification loop.