1 research outputs found
Molecular Characterization of Barrier Properties in Follicle-Associated Epithelium of Porcine Peyer's Patches Reveals Major Sealing Function of Claudin-4
The pig represents a preferred model for the analysis of intestinal
immunology. However, the barrier of the follicle-associated epithelium (FAE)
covering porcine Peyer's patches (PP) has not yet been characterized in
detail. This study aimed to perform this characterization in order to pave the
way toward an understanding of the functional contribution of epithelial
barrier properties in gut immunology. Porcine tissue specimens were taken from
the distal small intestine in order to obtain electrophysiological data of PP
FAE and neighboring villous epithelium (VE), employing the Ussing chamber
technique. Transepithelial resistance (TER) and paracellular fluorescein flux
were measured, and tissues were morphometrically compared. In selfsame
tissues, expression and localization of major tight junction (TJ) proteins
(claudin-1, -2, -3, -4, -5, and -8) were analyzed. PP FAE specimens showed a
higher TER and a lower apparent permeability for sodium fluorescein than VE.
Immunoblotting revealed an expression of all claudins within both epithelia,
with markedly stronger expression of the sealing TJ protein claudin-4 in PP
FAE compared with the neighboring VE. Immunohistochemistry confirmed the
expression and localization of all claudins in both PP FAE and VE, with
stronger claudin-4 abundance in PP FAE. The results are in accordance with the
physiological function of the FAE, which strongly regulates and limits antigen
uptake determining a mandatory transcellular route for antigen presentation,
highlighting the importance of this structure for the first steps of the
intestinal immune response. Thus, this study provides detailed insights into
the specific barrier properties of the porcine FAE covering intestinal PP, at
the interface of intestinal immunology and barriology