TY - JOUR
T1 - Cytokine-stimulated nitric oxide production inhibits adenylyl cyclase and cAMP-dependent secretion in cholangiocytes
AU - Spirlì, Carlo
AU - Fabris, Luca
AU - Duner, Elena
AU - Fiorotto, Romina
AU - Ballardini, Giorgio
AU - Roskams, Tania
AU - Larusso, Nicholas F.
AU - Sonzogni, Aurelio
AU - Okolicsanyi, Lajos
AU - Strazzabosco, Mario
N1 - Funding Information:
Supported by Telethon (grant E-873) and Ministero dell'Università e della Ricerca Scientifica e Tecnologica (cofinanziamento 1998, grant 9806210866, cofinanziamento 2000, grant MM06215421, coordinated by L.O.).
PY - 2003/3/1
Y1 - 2003/3/1
N2 - Background & Aims: The biliary epithelium is involved both in bile production and in the inflammatory/reparative response to liver damage. Recent data indicate that inflammatory aggression to intrahepatic bile ducts results in chronic progressive cholestasis. Methods: To understand the effects of nitric oxide on cholangiocyte secretion and biliary tract pathophysiology we have investigated: (1) the effects of proinflammatory cytokines on NO production and expression of the inducible nitric oxide synthase (NOS2), (2) the effects of NO on cAMP-dependent secretory mechanisms, and (3) the immunohistochemical expression of NOS2 in a number of human chronic liver diseases. Results: Our results show that: (1) tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, synergically stimulate NO production in cultured cholangiocytes through an increase in NOS2 gene and protein expression; (2) micromolar concentrations of NO inhibit forskolin-stimulated cAMP production by adenylyl cyclase (AC), cyclic adenosine monophosphate (cAMP)-dependent fluid secretion, and cAMP-dependent Cl- and HCO3 - transport mediated by cystic fibrosis transmembrane conductance regulator (CFTR) and anion exchanger isoform 2, respectively; (3) cholestatic effects of NO and of proinflammatory cytokines are prevented by NOS-2 inhibitors and by agents (manganese(Ill)-tetrakis(4-benzoic acid)porphyrin [MnTBAP], urate, trolox) able to block the formation of reactive nitrogen oxide species (RNOS); (4) NOS2 expression is increased significantly in the biliary epithelium of patients with primary sclerosing cholangitis (PSC). Conclusions: Our findings show that proinflammatory cytokines stimulate the biliary epithelium to generate NO, via NOS2 induction, and that NO causes ductular cholestasis by a RNOS-mediated inhibition of AC and of cAMP-dependent HCO3 - and Cl- secretory mechanisms. This pathogenetic sequence may contribute to ductal cholestasis in inflammatory cholangiopathies.
AB - Background & Aims: The biliary epithelium is involved both in bile production and in the inflammatory/reparative response to liver damage. Recent data indicate that inflammatory aggression to intrahepatic bile ducts results in chronic progressive cholestasis. Methods: To understand the effects of nitric oxide on cholangiocyte secretion and biliary tract pathophysiology we have investigated: (1) the effects of proinflammatory cytokines on NO production and expression of the inducible nitric oxide synthase (NOS2), (2) the effects of NO on cAMP-dependent secretory mechanisms, and (3) the immunohistochemical expression of NOS2 in a number of human chronic liver diseases. Results: Our results show that: (1) tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, synergically stimulate NO production in cultured cholangiocytes through an increase in NOS2 gene and protein expression; (2) micromolar concentrations of NO inhibit forskolin-stimulated cAMP production by adenylyl cyclase (AC), cyclic adenosine monophosphate (cAMP)-dependent fluid secretion, and cAMP-dependent Cl- and HCO3 - transport mediated by cystic fibrosis transmembrane conductance regulator (CFTR) and anion exchanger isoform 2, respectively; (3) cholestatic effects of NO and of proinflammatory cytokines are prevented by NOS-2 inhibitors and by agents (manganese(Ill)-tetrakis(4-benzoic acid)porphyrin [MnTBAP], urate, trolox) able to block the formation of reactive nitrogen oxide species (RNOS); (4) NOS2 expression is increased significantly in the biliary epithelium of patients with primary sclerosing cholangitis (PSC). Conclusions: Our findings show that proinflammatory cytokines stimulate the biliary epithelium to generate NO, via NOS2 induction, and that NO causes ductular cholestasis by a RNOS-mediated inhibition of AC and of cAMP-dependent HCO3 - and Cl- secretory mechanisms. This pathogenetic sequence may contribute to ductal cholestasis in inflammatory cholangiopathies.
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U2 - 10.1053/gast.2003.50100
DO - 10.1053/gast.2003.50100
M3 - Article
C2 - 12612912
AN - SCOPUS:0037370065
VL - 124
SP - 737
EP - 753
JO - Gastroenterology
JF - Gastroenterology
SN - 0016-5085
IS - 3
ER -