PAR-2 activation in intestinal epithelial cells potentiates interleukin-1beta-induced chemokine secretion via MAP kinase signaling pathways.
Intestinal epithelial cells can be induced to secrete the chemokine interleukin (IL)-8 during inflammation. The PAR-2 receptor is believed to play a proinflammatory role and is expressed in gut epithelial cells. The aim was to investigate PAR-2 signaling in Caco-2 intestinal epithelial cells, with respect to chemokine secretion. Activation of PAR-2 by high concentrations of the synthetic activating peptide (SLIGKV) did not induce secretion of IL-8, in contrast to stimulation with IL-1beta. However, upon simultaneous treatment with activating peptide and IL-1beta, a potentiating effect of PAR-2 stimulation was seen, resulting in a fivefold increase of IL-8. Available data suggest that NF-kappaB activation is required for IL-8 gene expression. Unlike IL-1beta, PAR-2 stimulation did not activate NF-kappaB, which may explain the lack of IL-8 expression. However, PAR-2 stimulation led to rapid phosphorylation of two MAP kinases, p38 MAPK and ERK1/2. ERK1/2 is known to activate the transcription factor AP-1, also involved in upregulation of IL-8 gene transcription. Inhibition of p38 MAPK led to decreased IL-8 following stimulation with IL-1beta and/or activating peptide. These results suggest that maximal IL-8 expression requires coordination of several signaling pathways. Thus, identifying antagonists to the PAR-2 receptor may be beneficial by inhibiting potentiation of a proinflammatory response, through inhibition of p38 and ERK MAP kinases.
Fyfe
Meredith
M
Department of Molecular Pharmacology, AstraZeneca R&D, Pepparedsleden 1-3, 431 83 Mölndal, Sweden. meredith.fyfe@astrazeneca.com
Bergström
Monica
M
Aspengren
Sara
S
Peterson
Anders
A
D000818:Animals; D015153:Blotting, Western; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D018925:Chemokines / Q000378:metabolism; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000166:cytology*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D007249:Inflammation; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D007422:Intestines / Q000166:cytology*; D008024:Ligands; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000096:biosynthesis; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D018925:Chemokines; D007375:Interleukin-1; D016209:Interleukin-8; D008024:Ligands; D016328:NF-kappa B; D010455:Peptides; D012333:RNA, Messenger; D044464:Receptor, PAR-2; D018808:Transcription Factor AP-1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases