ABSTRACT
We investigated prostanoid biogenesis in human colonic fibroblasts (CCD-18Co and 5 primary fibroblast cultures) and epithelial cell lines (NCM460, T84, HT-29, and LS 174T) and the effect of PGE2 on fibroblast morphology. Cytokine-stimulated PGE2 production was measured. PGH synthase-1 and -2 (PGHS-1 and -2) protein and mRNA expression were evaluated. Basal PGE2 levels were low in all cell types (0.15-6.47 ng/mg protein). Treatment for 24 h with interleukin-1beta (IL-1beta; 10 ng/ml) or tumor necrosis factor-alpha (50 ng/ml), respectively, elicited maximal 25- and 6-fold inductions of PGE2 synthesis in CCD-18Co cultures and similar results in primary fibroblast cultures; maximal inductions with IL-1beta in colonic epithelial cell lines were from zero to fivefold. Treatment of CCD-18Co fibroblasts with IL-1beta caused maximal 21- and 53-fold increases, respectively, in PGHS-2 protein and mRNA levels without altering PGHS-1 expression. PGE2 (0.1 micromol/l) elicited a dramatic shape change in selected fibroblasts. Colonic fibroblasts are potentially important as cytokine targets and a source of and target for colonic prostanoids in vivo.
Subject(s)
Colon/metabolism , Colonic Neoplasms/metabolism , Cytokines/pharmacology , Dinoprostone/metabolism , Intestinal Mucosa/metabolism , Isoenzymes/biosynthesis , Prostaglandin-Endoperoxide Synthases/biosynthesis , Cell Line , Colon/cytology , Colon/drug effects , Colonic Neoplasms/pathology , Cyclooxygenase 1 , Cyclooxygenase 2 , Cytokines/physiology , Enzyme Induction , Fibroblasts/metabolism , Humans , Interleukin-1/pharmacology , Intestinal Mucosa/cytology , Intestinal Mucosa/drug effects , Isoenzymes/genetics , Kinetics , Membrane Proteins , Prostaglandin-Endoperoxide Synthases/genetics , RNA, Messenger/genetics , Transcription, Genetic/drug effects , Tumor Cells, Cultured , Tumor Necrosis Factor-alpha/pharmacologyABSTRACT
A newly emerging view of fibroblasts is that they are vital for initiating inflammation and respond to and direct the activities of leukocytes. Human fibroblasts can express CD40, an activation Ag the ligand of which is displayed by activated leukocytes. We demonstrate here that CD40 engagement on human lung fibroblasts dramatically increases proinflammatory PGE2 synthesis. This up-regulation is mediated through an induction of cyclooxygenase-2 (Cox-2) since Cox-2-selective inhibitors block the up-regulation. Western and Northern blot analyses demonstrated that Cox-2 protein and mRNA are dramatically increased in fibroblasts following CD40 engagement. We conclude that CD40 is a major pathway in human fibroblasts for the induction of Cox-2. There is intense interest in devising strategies for disruption of the CD40-CD40 ligand system to blunt inflammation. Such an intervention would be expected to attenuate the up-regulation of fibroblast Cox-2 and PGE2 production at the site of tissue injury.
