SummaryAlthough enhanced lymphocyte trafficking is associated with colitis formation, little information about its regulation is available. The aim of this study was to examine how the murine liver and activation-regulated chemokine (mLARC/CCL20) contributes to lymphocyte recruitment in concert with vascular adhesion molecules in murine chronic experimental colitis. T and B lymphocytes isolated from the spleen were fluorescence-labelled and administered to recipient mice. Lymphocyte adhesion to microvessels of the colonic mucosa and submucosa was observed with an intravital microscope. To induce colitis, the mice received two cycles of treatment with 2% dextran sodium sulphate (DSS). In some of the experiments antibodies against the adhesion molecules or anti-mLARC/CCL20 were administered, or CC chemokine receptor 6 (CCR6) of the lymphocytes was desensitized with excess amounts of mLARC/CCL20. Significant increases in T and B cell adhesion to the microvessels of the DSS-treated mucosa and submucosa were observed. In chronic colitis, the accumulation of lymphocytes was significantly inhibited by anti-mucosal addressin cell adhesion molecule (MAdCAM)-1 mAb, but not by anti-vascular cell adhesion molecule-1. In DSS-treated colonic tissue, the expression of mLARC/CCL20 was significantly increased, the blocking of mLARC/CCL20 by monoclonal antibody or the desensitization of CCR6 with mLARC/CCL20 significantly attenuated the DSS-induced T and B cell accumulation. However, the combination of blocking CCR6 with MAdCAM-1 did not further inhibit these accumulations. These results suggest that in chronic DSS-induced colitis, both MAdCAM-1 and mLARC/CCL20 may play important roles in T and B lymphocyte adhesion in the inflamed colon under flow conditions.
. Chronic allergy to dietary ovalbumin induces lymphocyte migration to rat small intestinal mucosa that is inhibited by MAdCAM-1. Am J Physiol Gastrointest Liver Physiol 286: G702-G710, 2004. First published December 11, 2003 10.1152/ajpgi.00183.2003.-Few models have described a chronic food allergy with morphological changes in the intestinal mucosa. Here we established an ovalbumin (OVA)-induced, cell-mediated, allergic rat model and examined lymphocyte migration in the gut. Brown Norway rats were intraperitoneally sensitized to OVA and then given 10 mg OVA/day by gastric intubation for 6 wk. Lymphocyte subsets and adhesion molecules were examined immunohistochemically, and the migration of T lymphocytes to microvessels of Peyer's patches and villus mucosa was observed by using an intravital microscope. Serum OVA-specific IgG and IgE levels were increased in animals repeatedly exposed to OVA. Significant villus atrophy and increased crypt depth was accompanied by increased infiltration of T lymphocytes in the small intestinal mucosa of the group given OVA. Expression of rat mast cell protease II and of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) was also increased in these groups. The administration of anti-MAdCAM-1 antibody significantly attenuated the OVA-induced changes in the mucosal architecture and in CD4 T lymphocyte infiltration. Intravital observation demonstrated that in rats with a chronic allergy, T lymphocytes significantly accumulated in villus microvessels as well as in Peyer's patches via a MAdCAM-1-dependent process. Our model of chronic food allergy revealed that lymphocyte migration was increased with MAdCAM-1 upregulation.Brown Norway rats; rat mast cell protease II; delayed type hypersensitivity; Peyer's patch; intercellular adhesion molecule-1 THE CLINICAL MANIFESTATIONS of allergic reactions from food intolerance may be localized to the gut, including abdominal discomfort, nausea, vomiting, and diarrhea. Type I or IgEmediated allergic reactions are involved in early-phase symptoms of food allergy (6,8). On the other hand, cell-mediated reactions are also involved in the late phase and symptoms are often prolonged, causing mucosal damage such as crypt hyperplasia, villus atrophy, and lymphocyte infiltration (11,13,27,30). Because human research is restricted, animal models of food allergies would be of significant value. Several efforts have been made to develop rodent models of food allergy (10,14,32). However, few models have been validated for studying the effects of chronic antigen exposure or for relevance to clinical situations involving both IgE-and cell-mediated reactions (21,22,28). Although several groups (10) have investigated the effect of repeated oral challenge in rats with IgEmediated hypersensitivity, lymphocyte infiltration was not obvious in the intestinal mucosa of these animals. Only a recent report by Yang et al. (36) has demonstrated that the oral antigen challenge of sensitized Sprague-Dawley rats induces sustained epithelial dysfunction with inflammator...
Ceramides have emerged as key participants in the signaling pathway of cytokines and apoptosis. We previously revealed that phorbol 12-myristate 13-acetate (PMA) induced experimental ulcers in rat gastric mucosa. In this study, we investigated the role of ceramide in ulcer formation and its relation to the activation of transcription factors and apoptosis. PMA was subserosally injected to rat glandular stomach. Fumonisin B1 (FB1), an inhibitor of ceramide synthase, was administered together with the PMA. The time course of ceramide content was quantified using thin layer chromatography and the number of apoptotic cells was determined by immunohistochemistry. The activation of transcription factor nuclear factor-B (NF-B) or activator protein-1 (AP-1) was evaluated using an electrophoretic mobility shift assay. The administration of FB1 attenuated PMA-induced gastric ulcer formation in a dosedependent manner. Before the ulcers became obvious, the ceramide content (C18 and C24 ceramide) increased significantly in the gastric wall. The activation of NF-B and AP-1 and an increase in the number of apoptotic cells were also observed. Both of these were significantly inhibited by the coadministration of FB1. However, NF-B inhibitors attenuated gastric ulcer formation without affecting the ceramide content or the number of apoptotic cells. Ceramide formation in the stomach significantly contributes to PMA-induced tissue damage, possibly via the activation of transcription factors and an increase in apoptosis in the gastric mucosa. However, after the increase in ceramide levels, the NF-B and apoptosis pathways may be separately involved in ulcer formation.
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