In situ demonstration of intraepithelial lymphocyte adhesion to villus microvessels of the small intestine

Abstract

The recirculation of lymphocytes through the intestinal mucosa is important for specific immune defense, but the origin and differentiation of intraepithelial lymphocytes (IEL) are not fully understood. The present study therefore used intravital microscopy to investigate the migration of IEL to the villus mucosa and Peyer's patches of the small intestine. IEL were separated from inverted murine small intestine and mesenteric lymph node (MLN) T cells were also isolated. The adhesion of fluorescence-labeled lymphocytes to postcapillary venules (PCV) of Peyer's patches and arcade microvessels of small intestinal villi was observed after injection. In some experiments, the effect of antibodies against adhesion molecules on cell kinetics were investigated. IEL time-dependently accumulated in villus microvessels of the small intestine, whereas few MLN cells did. Few IEL adhered to the PCV of Peyer's patches. IEL were shown to express alpha(E)beta(7)-integrin but not L-selectin. The accumulation of IEL in villus archade was significantly inhibited by antibody against beta(7)-integrin or mucosal addressin cell adhesion molecules (MAdCAM)-1, but not by alpha(E)-integrin. The combined blocking of beta(7)-integrin and MAdCAM-1 further attenuated the sticking of IEL in this area, although it did not entirely block the IEL adherence. The adherence of CD4(+) or TCRalphabeta IEL to villus microvessels was significantly greater than that of CD4(-) or TCRgammadelta IEL. It was demonstrated in situ for the first time that IEL adhered selectively to the villus microvessels of the small intestine partly via beta(7) and MAdCAM-1.

Intravital microscopy comparing T lymphocyte trafficking to the spleen and the mesenteric lymph node

“…Several studies using static assays have shown the primary role of L-selectin-MAd-CAM-1 interactions in lymphocyte trafficking to the MLN as well as the lesser importance of ␣ 4 ␤ 7 -integrinMAdCAM-1 binding (4,48). Intravital studies of vessels within the mesentery or HEV within Peyer's patches (both of which express MAdCAM-1) have shown that rolling of leukocytes can occur on MAd-CAM-1 in both an L-selectin-and ␣ 4 ␤ 7 -integrin-dependent fashion (4,19). Therefore, we undertook these investigations to further characterize the behavior of lymphocyte trafficking to the MLN and spleen to determine the WSR in the MLN and spleen and to compare the contributions of the two known MAdCAM-1-binding ligands to T lymphocyte homing in both organs.…”

Demonstration of functional role of TECK/CCL25 in T lymphocyte-endothelium interaction in inflamed and uninflamed intestinal mucosa

“…There was a strong surface expression of ␣4-and ␤7-integrin and CD11a in LPLs, but L-selectin was only slightly expressed. IELs used in the migration studies comprised four subpopulations (65% CD4-negative/CD8-positive cells, 8% CD4-positive/CD8-negative cells, 22% double-negative cells, and 5% double-positive cells) (11). The IELs always showed a strong expression of ␣ E-and ␤7-integrin molecules on their surface.…”

“…Suitable area of the microcirculation in small intestinal mucosa was observed from the mucosal surface with an inverted-type fluorescence microscope (Diaphot TMD-2S; Nikon, Tokyo, Japan) and was recorded on a videotape. Behavior of fluorescently labeled lymphocytes was visualized on the television monitor through the fluorescence microscope equipped with a silicon intensified target image tube camera with a contrast-enhancing unit (model C-2400-08; Hamamatsu Photonics, Shizuoka, Japan) according to the method described previously (7,11,16). Epiillumination was achieved with filters of excitation at 470-490 nm and emission at 520 nm.…”

“…These results suggest that the TECK/CCL25-CCR9 pathway is essential for the appearance of IELs in small intestinal mucosa. Although there is little information about the exact route and mechanisms by which IELs reach the intestinal epithelium, the TECK/CCL25-CCR9 pathway may play some important roles in the development and trafficking of IELs (11,24).…”

Role of the gut as a primary lymphoid organ

“…One population originates from peripheral T cells; after responding to antigens in the Peyer patches or the mesenteric lymph nodes, these cells up-regulate expression of ␣4␤7 integrin and chemokine receptor CCR9 and home to the gut mucosa [2][3][4]. These conventional T-IEL have the phenotype of peripheral antigen-experienced cells; i.e.…”