Inhibition of 5-lipoxygenase induces cell growth arrest and apoptosis in rat Kupffer cells: implications for liver fibrosis.
The existence of an increased number of Kupffer cells is recognized as critical in the initiation of the inflammatory cascade leading to liver fibrosis. Because 5-lipoxygenase (5-LO) is a key regulator of cell growth and survival, in the current investigation we assessed whether inhibition of the 5-LO pathway would reduce the excessive number of Kupffer cells and attenuate inflammation and fibrosis in experimental liver disease. Kupffer cells were the only liver cell type endowed with a metabolically active 5-LO pathway (i.e., expressed mRNAs for 5-LO, 5-LO-activating protein [FLAP], and leukotriene [LT] C4 synthase and generated LTB4 and cysteinyl-LTs). Both the selective 5-LO inhibitor AA861 and the FLAP inhibitor BAY-X-1005 markedly reduced the number of Kupffer cells in culture. The antiproliferative properties of AA861 and BAY-X-1005 were associated with the occurrence of condensed nuclei, fragmented DNA, and changes in DNA content and cell cycle frequency distribution consistent with an apoptotic process. In vivo, in carbon tetrachloride-treated rats, BAY-X-1005 had a significant antifibrotic effect and reduced liver damage and the hepatic content of hydroxyproline. Together, these findings indicate a novel mechanism by which inactivation of the 5-LO pathway could disrupt the sequence of events leading to liver inflammation and fibrosis.
Titos
Esther
E
DNA Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona 08036, Spain.
Clària
Joan
J
Planagumà
Anna
A
López-Parra
Marta
M
Villamor
Neus
N
Párrizas
Marcelina
M
Carrió
Anna
A
Miquel
Rosa
R
Jiménez
Wladimiro
W
Arroyo
Vicente
V
Rivera
Francisca
F
Rodés
Joan
J
D000818:Animals; D017209:Apoptosis; D016227:Benzoquinones / Q000494:pharmacology; D002455:Cell Division; D002478:Cells, Cultured; D007728:Kupffer Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D008106:Liver Cirrhosis, Experimental / Q000188:drug therapy* / Q000473:pathology; D008954:Models, Biological; D011804:Quinolines / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats
D016227:Benzoquinones; D016859:Lipoxygenase Inhibitors; D011804:Quinolines; C079315:2-(4-(quinolin-2-yl-methoxy)phenyl)-2-cyclopentylacetic acid; C036837:2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone