title: Adenosine is a negative regulator of NF-kappaB and MAPK signaling in human intestinal epithelial cells.
abstract: Previous studies suggest that adenosine possesses anti-inflammatory properties, however, the mechanisms by which adenosine affects immune function remain unclear, particularly in the intestine. In this study, we hypothesized that adenosine directly affects pro-inflammatory gene expression in intestinal epithelial cells through modulation of NF-kappaB signaling. HT-29 cells were treated with adenosine prior to incubation with various stimuli and pro-inflammatory gene expression and signal transduction analyzed. Adenosine pretreatment resulted in a reduction in IL-8 expression and secretion in response to TNF-alpha, IL-1, LPS, and PMA. This effect was paralleled by inhibition of kappaB-driven luciferase expression and a reduction in recruitment of NF-kappaB to the IL-8 promoter. Pretreatment of HT-29 cells also resulted in reduced ERK, p38, and JNK MAPK phosphorylation, following TNF-alpha treatment. The observed effects in this study occurred independently of known surface adenosine receptors. This study identifies adenosine as a potent negative regulator of pro-inflammatory signaling in intestinal epithelial cells.
authors.affiliation: Gastrointestinal Research Unit, University of Alberta, Edmonton, Alberta, Canada T6G 2N8.
authors.forename: Humberto B
authors.initials: HB
authors.lastname: Jijon
authors.forename: John
authors.initials: J
authors.lastname: Walker
authors.forename: Frank
authors.initials: F
authors.lastname: Hoentjen
authors.forename: Hugo
authors.initials: H
authors.lastname: Diaz
authors.forename: Julia
authors.initials: J
authors.lastname: Ewaschuk
authors.forename: Christian
authors.initials: C
authors.lastname: Jobin
authors.forename: Karen L
authors.initials: KL
authors.lastname: Madsen
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001483:Base Sequence; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects* / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D000893:Anti-Inflammatory Agents; D007375:Interleukin-1; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D018047:Receptors, Purinergic P1; D014409:Tumor Necrosis Factor-alpha; D000241:Adenosine; D013755:Tetradecanoylphorbol Acetate