title: Site differences of Toll-like receptor expression in the mucous epithelium of rat small intestine.
abstract: Toll-like receptors (TLRs) are known to recognize pathogen-associated molecular patterns and might function as receptors to detect microbes. In this study, the distribution of TLR-2, -4 and -9 were immunohistochemically investigated in the rat small intestine. As a result, TLR-2 was detected in the striated borders of villous columnar epithelial cells throughout the small intestine, except for the apices of a small number of intestinal villi. TLR-4 and -9 were detected in the striated borders of the villous columnar epithelial cells only in the duodenum. TLR-4-immunopositive minute granules were found in the apical cytoplasms of epithelial cells, subepithelial spaces and blood capillary lumina. TLR-2 and -4 were detected in the striated borders of undifferentiated epithelial cells and in the luminal substances of the intestinal crypts throughout the small intestine, but TLR-9 was not detected in the crypts throughout the small intestine. Only TLR-4 was detected in the secretory granules of Paneth cells in both the jejunal and ileal intestinal crypts. These findings suggest that duodenal TLRs might monitor indigenous bacteria proliferation in the upper alimentary tract, that TLR-2 might also monitor the proliferation of colonized indigenous bacteria throughout the small intestine, that the lack of TLR-2 at the villous apices might contribute to the settlement of indigenous bacteria, and that TLR-2 and -4 are secreted from intestinal crypts.
authors.affiliation: Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Mantani
authors.forename: A
authors.initials: A
authors.lastname: Kamezaki
authors.forename: K G S
authors.initials: KG
authors.lastname: Udayanga
authors.forename: E-i
authors.initials: EI
authors.lastname: Takahara
authors.forename: W M
authors.initials: WM
authors.lastname: Qi
authors.forename: J
authors.initials: J
authors.lastname: Kawano
authors.forename: T
authors.initials: T
authors.lastname: Yokoyama
authors.forename: N
authors.initials: N
authors.lastname: Hoshi
authors.forename: H
authors.initials: H
authors.lastname: Kitagawa
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D051195:Toll-Like Receptor 2 / Q000032:analysis* / Q000096:biosynthesis; D051197:Toll-Like Receptor 4 / Q000032:analysis* / Q000096:biosynthesis; D051217:Toll-Like Receptor 9 / Q000032:analysis* / Q000096:biosynthesis
chemical_list: C495343:Tlr2 protein, rat; C495347:Tlr4 protein, rat; C489640:Tlr9 protein, rat; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9