title: Effect of corticosteroids on nitric oxide production in inflammatory bowel disease: are leukocytes the site of action?
abstract: Nitric oxide (NO) production is increased in the human colonic mucosa in intestinal inflammation. We examined the effect of corticosteroids and the role of mononuclear cells in this production. Colonic biopsies from patients with ulcerative colitis and normal controls were cultured with either budesonide or prednisolone in the presence of proinflammatory cytokines. Human mixed mononuclear cells (MMCs) were cocultured with HT-29 cells stimulated with IFN-gamma and LPS in the presence or absence of corticosteroids. Nitrite production was measured in supernatants by a modification of the Griess reaction, and inducible NO synthase (iNOS) mRNA expression was studied in colonic tissue by RT-PCR. Both steroids significantly suppressed the nitrite production and iNOS mRNA expression in inflamed colonic biopsies from ulcerative colitis patients and in cytokine-stimulated normal colonic biopsies but not in cytokine-stimulated HT-29 cells. Nitrite production by HT-29 cells was significantly increased (P < 0.01) in cocultures with MMCs stimulated with IFN-gamma and LPS. The presence of either prednisolone or budesonide significantly (P < 0.01) suppressed nitrite production from cocultures of HT-29 cells and MMCs but not from cultures of HT-29 cells stimulated with conditioned media from activated MMCs. Interestingly, stimulation of HT-29 with conditioned media from MMCs pretreated with steroids before stimulation with LPS and IFN-gamma induced a significantly (P < 0.01) lower nitrite production. These results suggest that the inhibitory effect of corticosteroids on the NO production in the intestinal inflammation might be via the inhibition of MMC-produced mediators responsible for NO production by colonic epithelial cells.
authors.affiliation: Department of Pharmacology, University of Bath, Bath, United Kingdom.
authors.forename: John D
authors.initials: JD
authors.lastname: Linehan
authors.forename: George
authors.initials: G
authors.lastname: Kolios
authors.forename: Vassilis
authors.initials: V
authors.lastname: Valatas
authors.forename: Duncan A F
authors.initials: DA
authors.lastname: Robertson
authors.forename: John
authors.initials: J
authors.lastname: Westwick
mesh_terms: D019819:Budesonide / Q000494:pharmacology; D002460:Cell Line; D003093:Colitis, Ulcerative / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011239:Prednisolone / Q000494:pharmacology
chemical_list: D005938:Glucocorticoids; D009569:Nitric Oxide; D019819:Budesonide; D011239:Prednisolone; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II