Stress induces more serious barrier dysfunction in follicle-associated epithelium than villus epithelium involving mast cells and protease-activated receptor-2

Psychological stress has been associated with intestinal epithelial hyperpermeability, the basic process in various functional and organic bowel diseases. In the present study, we aimed to clarify the differences and underlining mechanisms in stress-induced barrier disruption in functionally and structurally distinct epitheliums, including the villus epithelium (VE) and follicle-associated epithelium (FAE), a specialized epithelium overlaid the domes of Peyer’s lymphoid follicles. Employing an Ussing Chamber system, the epithelial permeability was assessed in rats following water avoidance stress (WAS) in vivo and in mucosa tissues exposed to corticotropin-releasing factor (CRF) ex vivo. Decreased transepithelial resistance (TER) and increased paracellular and transcellular macromolecular permeability in colon, ileal VE and FAE had been observed in WAS rats and in CRF-exposed mucosa. Especially, the barrier dysfunction was more serious in the FAE. Moreover, WAS upregulated the expression of mast cell tryptase and protease-activated receptor-2 (PAR2), which positively correlated with epithelial conductance. Mast cell stabilizer cromolyn sodium obviously alleviated the barrier disruption induced by WAS in vivo and CRF in vitro. Serine protease inhibitor aprotinin and FUT-175, and selective PAR2 antagonist ENMD-1068 effectively inhibited the CRF-induced FAE hyperpermeability. Altogether, it concluded that the FAE was more susceptible to stress, and the mast cells and PAR2 signaling played crucial roles in this process.