Induction of mucosal tolerance in Peyer‘s patch—deficient, ligated small bowel loops
Thomas A. Kraus, Jens Brimnes, Christine Muong, Jian-Hua Liu, Thomas M. Moran, Kelly A. Tappenden, Peter Boros, Lloyd Mayer
Thomas A. Kraus, Jens Brimnes, Christine Muong, Jian-Hua Liu, Thomas M. Moran, Kelly A. Tappenden, Peter Boros, Lloyd Mayer
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Research Article Immunology

Induction of mucosal tolerance in Peyer‘s patch—deficient, ligated small bowel loops

Abstract

To explore the requirement for M cells and the Peyer’s patch (PP) in induction of oral tolerance and address the potential in vivo role of intestinal epithelial cells as nonprofessional APCs, we have attempted to induce tolerance in mice with ligated small bowel loops without M cells and Peyer’s patches. A 2-centimeter section of vascularized small bowel was spliced away from the gut without disruption of the mesenteric attachments. We introduced OVA directly into the lumen of the loop prior to footpad immunization. By excising segments of bowel that contain PPs in some mice and segments without patches in others, we could study the necessity of the M cell and the underlying patch versus epithelial cells in induction of mucosal tolerance. We show that OVA-specific T cell proliferation and serum antibody responses are reduced in mice that have previously been given OVA both in PP-containing loops and in loops without patches. Furthermore, both high- and low-dose tolerance could be induced in the absence of PPs. Low-dose tolerance is associated with bystander suppression and requires IL-10, which indicates active suppression and the induction of regulatory cells. These data suggest that there is a critical role for components of the mucosal immune system other than PPs in antigen sampling and induction of oral tolerance.

Authors

Thomas A. Kraus, Jens Brimnes, Christine Muong, Jian-Hua Liu, Thomas M. Moran, Kelly A. Tappenden, Peter Boros, Lloyd Mayer

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Figure 2

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Microscopic evaluation of intestinal loops. E and M loops were excised 1...
Microscopic evaluation of intestinal loops. E and M loops were excised 10 days after surgery and fixed in 10% formalin for H&E staining or immediately fixed in glutaraldehyde for electron microscopy. Cross-sections were cut and stained with hematoxylin and counterstained with eosin. (A and B) Representative sections from the E loop (no PP). (C and D) Representative sections from the M loop. The PP is indicated by an arrow in C. Original magnification, ×10 (A and C) and ×40 (B and D). (E and F) Electron micrographs of a loop 10 days after surgery (E) compared with normal bowel (F) at ×40,000 magnification. Desmosomes (arrows) indicate the presence of tight junctions. As shown, cross-sections of the loops revealed normal architecture as well as an intact epithelium and no evidence of active inflammation. (G and H) Deconvolution micrograph demonstrating the presence of DCs in the lamina propria of distal jejunal segments in CD11c-GFP mice (G) and in controls (H). Note that the dendrites failed to reach the epithelium in these segments (in contrast to the distal ileum). A 3D reconstruction (supplemental data) further demonstrates the failure of DCs to invade the epithelium in this part of the small intestine.