Related Experiment Video
Updated: Apr 17, 2026

Functional Assessment of Intestinal Permeability and Neutrophil Transepithelial Migration in Mice using a Standardized Intestinal Loop Model
Published on: February 11, 2021
Pseudomonas fluorescens alters the intestinal barrier function by modulating IL-1β expression through hematopoietic
Ziad Alnabhani1, Nicolas Montcuquet, Kelly Biaggini
1*Université Paris-Diderot, Paris, France; †INSERM UMR1149, Paris, France; ‡Labex inflamex, Sorbonne Paris-Cité, Paris, France; §INSERM UMR1163, Laboratory of Intestinal Immunity, Paris, France; ‖Université Paris Descartes-Sorbonne Paris Cité and Institut Imagine, Paris, France; ¶LMSM EA 4312, Université de Rouen, Evreux, France; **Assistance Publique Hôpitaux de Paris, Hôpital Robert Debré, Paris, France; and ††INSERM UMR 1043, Centre de Physiopathologie de Toulouse, Université de Toulouse, Toulouse, France.
Background:
Ileal Crohn's disease is related to NOD2 mutations and to a gut barrier dysfunction. Pseudomonas fluorescens has also been associated with ileal Crohn's disease. The aim of this study was to determine the impact of P. fluorescens on the paracellular permeability in ileum and Peyer's patches.
Methods:
To explore this question, in vivo and ex vivo experiments were performed in wild-type, Nod2, Nod2, and IL-1R mice together with in vitro analyses using the Caco-2 (epithelial) and the THP-1 (monocyte) human cell lines.
Results:
Pseudomonas fluorescens increased the paracellular permeability of the intestinal mucosa through the secretion of IL-1β by the immune cell populations and the activation of myosin light chain kinase in the epithelial cells. Induction of the IL-1β pathway required the expression of Nod2 in the hematopoietic compartment, and muramyl dipeptide (a Nod2 ligand) had an inhibitory effect.
Conclusions:
Pseudomonas fluorescens thus alters the homeostasis of the epithelial barrier function by a mechanism similar to that previously observed for Yersinia pseudotuberculosis. This work further documents a putative role of psychrotrophic bacteria in Crohn's disease.
Related Concept Videos
Inflammatory Bowel Disease II: Ulcerative Colitis
Inflammatory Bowel Disease III: Crohn's Disease
Role Of Notch Signalling In Intestinal Stem Cell Renewal
Direct cell-to-cell contact is needed for the activation of Notch signaling. The signal is initiated when a notch ligand binds to a receptor on an adjacent cell, also...
Gut-Brain Axis
Gene Regulation in Microbial Communities: Quorum Sensing
Role of Ephrin-Eph Signalling in Intestinal Stem Cell Renewal

