title: Interleukin 1beta-induced production of H2O2 contributes to reduced sigmoid colonic circular smooth muscle contractility in ulcerative colitis.
abstract: We have shown that neurokinin A-induced contraction of human sigmoid circular muscle (HSCM) is reduced in patients with ulcerative colitis and that interleukin (IL)-1beta may play a role in this change. We now examine changes in the signal transduction pathway mediating neurokinin A-induced contraction of HSCM and explore the role of IL-1beta and of H(2)O(2) in these changes. In Fura 2-AM-loaded ulcerative colitis HSCM cells, neurokinin A- and caffeine-induced peak Ca(2+) increase and cell shortening were significantly reduced. In normal cells, neurokinin A-induced contraction was decreased by protein kinase C inhibitor chelerythrine and by calmodulin inhibitor CGS9343B [1,3-dihydro-1-[1-[(4-methyl-4H,6H-pyrrolo[1,2-a][4,1]-benzoxazepin-4-yl)methyl]-4-piperidinyl]-2H-benzimidazol-2-one (1:1) maleate]. In ulcerative colitis muscle cells, contraction was inhibited only by chelerythrine but not by CGS9343B. IL-1beta treatment of normal HSCM strips and cells reproduced the changes observed in ulcerative colitis. IL-1beta-induced reduction in caffeine-induced peak Ca(2+) increase and contraction was reversed by catalase, suggesting a role of H(2)O(2). IL-1beta-induced H(2)O(2) production was inhibited by mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059 (2'-amino-3'-methoxyflavone) and by cytosolic phospholipase A2 (cPLA(2)) inhibitor AACOCF3 (arachidonyltrifluoromethyl ketone), but neither by p38 MAPK inhibitor SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole] nor by nuclear factor-kappaB (NF-kappaB) inhibitory peptide NF-kappaB SN50 (H-Ala-Ala-Val-Ala-Leu-Leu-Pro-Ala-Val-Leu-Leu-Ala-Leu-Leu-Ala-Pro-Val-Gln-Arg-Lys-Arg-Gln-Lys-Leu-Met-Pro-OH). IL-1beta significantly increased the phosphorylation of extracellular signal-regulated kinase 1 (ERK1)/ERK2 MAPKs and cPLA(2) and IL-1beta-induced cPLA(2) phosphorylation was blocked by PD98059. We conclude that Ca(2+) stores of HSCM cells may be reduced in ulcerative colitis and that the signal transduction pathway of neurokinin A-induced contraction switches from calmodulin- and protein kinase C-dependent in normal cells to protein kinase C-dependent in ulcerative colitis cells. IL-1beta reproduces these changes, possibly by production of H(2)O(2) via sequential activation of MAPKs (ERK1/ERK2) and cPLA(2).
authors.affiliation: Department of Surgery, Brown Medical School and Rhode Island Hospital, 2 Dudley St., Suite 470, Providence, RI 02905, USA.
authors.forename: Weibiao
authors.initials: W
authors.lastname: Cao
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Vrees
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Potenti
authors.forename: Karen M
authors.initials: KM
authors.lastname: Harnett
authors.forename: Claudio
authors.initials: C
authors.lastname: Fiocchi
authors.forename: Victor E
authors.initials: VE
authors.lastname: Pricolo
mesh_terms: D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000502:physiology; D003093:Colitis, Ulcerative / Q000378:metabolism* / Q000503:physiopathology; D012809:Colon, Sigmoid / Q000473:pathology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D015288:Neurokinin A / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology
chemical_list: D002147:Calmodulin; D007375:Interleukin-1; D015288:Neurokinin A; D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D002118:Calcium