In vivo response of neutrophils and epithelial cells to lipopolysaccharide injected into the monkey ileum.
Since few previous studies have investigated the in vivo response of intestinal mucosa to the luminally administered lipopolysaccharide (LPS), we examined the cellular localization of exogenously applied LPS in the intestinal mucosa and the expression of Toll-like receptor (TLR) and IL-1 receptor-associated kinase (IRAK) in the epithelial cells of monkey ileum. FITC-labeled LPS was injected into the lumen of monkey ileum. Thirty minutes after the LPS injection, the ileal tissue was fixed and localization of FITC fluorescence in the ileal mucosa was examined. We applied Factor C immunohistochemistry to demonstrate the bioactivity of LPS taken up by the mucosal tissue. The expression of TLR4 and IRAK-1 in the epithelial cells was also examined by immunohistochemistry. FITC fluorescence was detected in the cells migrated into the epithelium and those in the lamina propria. The FITC-labeling cells were completely overlapped with the Factor C immunoreactive cells. These FITC-labeling/Factor C-positive cells were identified as neutrophils by the immunoelectron microscopic analysis. TLR4 and IRAK-1 were expressed at the apical membrane of the epithelial cells in the ileum of both control and FITC-LPS injected animals. These results suggest that intraluminal injection of LPS stimulates the transmigration of neutrophils into the epithelium and these neutrophils may uptake luminally applied LPS and possibly inactivate the enterotoxin. Expression of TLR4 and IRAK-1 in the epithelial cells suggests that epithelial cells may react to LPS and produce chemoattractant mediator to induce the neutrophil chemotaxis.
Imaeda
Hirotsugu
H
Department of Anatomy, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan.
Yamamoto
Hiroshi
H
Takaki
Atsushi
A
Fujimiya
Mineko
M
D000818:Animals; D060829:Arthropod Proteins; D004792:Enzyme Precursors / Q000378:metabolism / Q000648:ultrastructure; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D016650:Fluorescein-5-isothiocyanate; D007082:Ileum / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D007267:Injections; D053592:Interleukin-1 Receptor-Associated Kinases; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology*; D008251:Macaca; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D011494:Protein Kinases / Q000378:metabolism / Q000648:ultrastructure; D011956:Receptors, Cell Surface / Q000378:metabolism / Q000648:ultrastructure; D012697:Serine Endopeptidases / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D060829:Arthropod Proteins; D004792:Enzyme Precursors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D011494:Protein Kinases; D053592:Interleukin-1 Receptor-Associated Kinases; D012697:Serine Endopeptidases; C057151:Limulus clotting factor C; D016650:Fluorescein-5-isothiocyanate