Glycoconjugate Expression Defines the Origin and Differentiation Pathway of Intestinal M-cells

Abstract

SUMMARYIntestinal M-cells are specialized epithelial cells located in the domes of the gut-associated lymphoid tissues, which transport antigens from the lumen to the underlying lymphoid tissue, thereby initiating immune reactions. It is assumed that M-cells arise from stem cells in the crypts, from which they migrate to the top of the domes. To study the differentiation pathway of M-cells, we used the rabbit cecal lymphoid patch in which the M-cells express high levels of ␣ 1-2-linked fucose and N -acetyl-galactosamine residues in their apical membrane. Dome areas were labeled with fluorescein-and rhodamine-conjugated lectins specific for ␣ 1-2-linked fucose and N -acetyl-galactosamine in vivo and in vitro, and were observed with confocal laser scanning microscopy. Ultrathin sections were double labeled with lectin-gold conjugates and the labeling density was quantified by computer-based image analysis. All cecal patch M-cells expressed ␣ 1-2-linked fucose and N -acetyl-galactosamine, but the amount of the two saccharides varied considerably depending on the position of the M-cells at the base, flank, or top of the dome. In eight of 18 rabbits studied, radial strips of M-cells with common glycosylation patterns were observed, each strip associated with an individual crypt. Confocal microscopy revealed that lectinlabeled M-cells were not restricted to the dome epithelium but were also detected in the upper third of crypts surrounding the domes. The results show that M-cells are heterogeneous concerning the glycosylation pattern of membrane glycoconjugates. This pattern is modified as the M-cells differentiate and migrate from the base to the top of the dome. Radial strips of M-cells with a common proclivity of glycoconjugate expression suggest that those M-cells that derive from the same crypt have a clonal origin. The presence of (pre-) M-cells in the crypts surrounding the domes indicates that M-cells derive directly from undifferentiated crypt cells and do not develop from differentiated enterocytes.

Lectin Histochemical Detection of Special Sugars on the Mucosal Surfaces of the Rat Alimentary Tract

“…Our previous studies have clarified that the fundamental settlement sites of indigenous bacteria are the narrow apical portions of the intestinal villi in the rat small intestine and the intestinal superficial epithelial cells of the most luminal portion of the mucosa in the rat large intestine [8,9,21,22,42]. Sugars expressed on the mucosal surfaces are changed along the crypt-villous axis in the intestinal villi and the crypt-dome axis in the gutassociated-lymphatic tissues [13,31]. In our previous study, only two sugars, (GlcNAc) [2][3][4] and -D-Gal(1-3)DGalNAc, were strongly expressed in the glycocalyx in the striated border of late-apoptosis-stage villous columnar epithelial cells, but were not expressed in the other villous portions of rat jejunoileum [9].…”

Deficiency of Reproductive Tract α(1,2)Fucosylated Glycans and Normal Fertility in Mice with Targeted Deletions of the FUT1 or FUT2 α(1,2)Fucosyltransferase Locus

“…Similar considerations apply, for example, to the intestinal M cell, an H-antigen-positive epithelial cell that overlies mucosa-associated lymphoid tissues (17), to the ␣(1,2)fucosylated olfactory epithelium (10), to rare ␣(1,2)fucosylated enteroendocrine cells of the gastrointestinal tract (15,16), and to other cell types revealing restricted expression of ␣(1,2)fucosylated glycans in development and differentiation (39).…”

Special Sugar Expression on Apoptotic Epithelial Cells of Peyer's Patches and Intestinal Villi in Rat Small Intestine

“…The lectin-binding properties are changed along the crypt-villous axis in the intestinal villi and the crypt-dome axis in the gut-associated-lymphatic tissues [7,26]. In general, epithelial cells of the intestinal villi or the FAEs are generated in the intestinal crypts, followed by migration toward the tips of the intestinal villi or domes in the small intestine.…”