OmpC and the sigma(E) regulatory pathway are involved in adhesion and invasion of the Crohn's disease-associated Escherichia coli strain LF82.
Ileal lesions of 36.4% of patients with Crohn's disease (CD), an inflammatory bowel disease in humans, are colonized by pathogenic adherent-invasive Escherichia coli (AIEC), and high levels of antibodies directed against E. coli OmpC are present in 37-55% of CD patients. We therefore investigated the expression of OmpC and its role in the interaction of CD-associated adherent-invasive E. coli strain LF82 with intestinal epithelial cells. High osmolarity induced a significant increase in the ability of LF82 bacteria to interact with Intestine-407 cells, which correlates with increased OmpC expression. Deletion of ompC gene markedly decreased the adhesion and invasion levels of the corresponding mutant. A LF82-DeltaompR mutant impaired in OmpC and OmpF expression, showed decreased adhesion and invasion, and unlike a K-12-negative OmpR mutant did not express flagella and type 1 pili. Interestingly, the wild-type phenotype was restored when OmpC or OmpF expression was induced in the LF82-DeltaompR mutant. Overexpression of RpoE in the LF82-DeltaompR isogenic mutant restored a full wild-type phenotype without restoring OmpC expression. Increased expression of RpoE was observed in wild-type strain LF82 at high osmolarity. Hence, the role of OmpC in the AIEC LF82 adhesion and invasion is indirect and involves the sigma(E) regulatory pathway.
Rolhion
Nathalie
N
Univ Clermont 1, Pathogénie Bactérienne Intestinale, USC INRA 2018, Clermont-Ferrand F-63000, France.
Carvalho
Frédéric Antonio
FA
Darfeuille-Michaud
Arlette
A
D018829:Adhesins, Bacterial; D001422:Bacterial Adhesion / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D003424:Crohn Disease / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D004927:Escherichia coli Infections
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins