Enhanced production of IL-18 in butyrate-treated intestinal epithelium by stimulation of the proximal promoter region.
Expression of IL-18 in intestinal epithelial cells (IEC) has been implicated in Th1 cell-mediated chronic intestinal inflammation and anti-tumor immunity. However, physiological regulatory factors have not been identified. Besides their effects on proliferation and restitution, immunomodulatory functions have been attributed to short chain fatty acids (SCFA). We investigated the effect of SCFA (butyrate, propionate, acetate) on expression of IL-18 in IEC in vitro and in vivo. Expression of IL-18 mRNA and protein in human carcinoma-derived HT-29 and Caco-2 cells was analyzed by reverse transcription-PCR and Western blot. Transcriptional regulation of IL-18 gene expression was determined by transient transfection of wild-type and mutated IL-18 promoter. Further, in vivo expression of IL-18 in the intestine from butyrate-treated and untreated mice was assessed by immunohistochemistry. IL-18 mRNA and the IL-18 protein were expressed in IEC, while IL-18 secretion was not observed. Butyrate and acetate increased intracellular IL-18 content in a time- and dose-dependent fashion. In contrast to proinflammatory stimuli butyrate potently activated the IL-18 promoter, indicating that IL-18 is regulated at the transcriptional level by SCFA. Furthermore, a 108-bp sequence in the proximal region was identified to be essential for IL-18 promoter activation by butyrate. As proof of principle butyrate effects were confirmed in vivo by demonstration of increased IL-18 protein expression in IEC from butyrate-treated mice. In conclusion, SCFA up-regulate IL-18 protein expression in IEC, suggesting a potential regulatory contribution of these luminal constituents to T cell mediated inflammatory and neoplastic intestinal conditions.
Department of Hematology, University Hospital Frankfurt, Germany.
Uwe
U
Kalina
Noriko
N
Koyama
Tomoko
T
Hosoda
Heike
H
Nuernberger
Kazuto
K
Sato
Dieter
D
Hoelzer
Frank
F
Herweck
Tobias
T
Manigold
Manfred V
MV
Singer
Siegbert
S
Rossol
Ulrich
U
Böcker
D000085:Acetates / Q000494:pharmacology*; D000230:Adenocarcinoma / Q000473:pathology; D000818:Animals; D002087:Butyrates / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D020382:Interleukin-18 / Q000096:biosynthesis* / Q000235:genetics; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D000085:Acetates; D002087:Butyrates; D020382:Interleukin-18; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm