Inhibition of inducible nitric oxide synthase protects against liver injury induced by mycobacterial infection and endotoxins.
OBJECTIVE
Bacillus Calmette Guerin (BCG) infection causes hepatic injury following granuloma formation and secretion of cytokines which render mice highly sensitive to endotoxin-mediated hepatotoxicity. This work investigates the role of inducible nitric oxide synthase (iNOS) in liver damage induced by BCG and endotoxins in BCG-infected mice.


METHODS
Liver injury and cytokine activation induced by BCG and by LPS upon BCG infection (BCG/LPS) were compared in wild-type and iNOS-/- mice.


RESULTS
iNOS-/- mice infected with living BCG are protected from hepatic injury when compared to wild-type mice which express iNOS protein in macrophages forming hepatic granulomas. In addition, iNOS-/- mice show a decrease in BCG-induced IFN-gamma serum levels. LPS challenge in BCG-infected mice strongly activates iNOS in the liver and spleen of wild-type mice which show important liver damage associated with a dramatic increase in TNF and IL-6 and also Th1 type cytokines. In contrast, iNOS-/- mice are protected from liver injury after BCG/LPS challenge and their TNF, IL-6 and Th1 type cytokine serum levels raise moderately.


CONCLUSIONS
These results demonstrate that nitric oxide (NO) from iNOS is involved in hepatotoxicity induced by both mycobacterial infection and endotoxin effects upon BCG infection and that inhibition of NO from iNOS protects from liver injuries.
Guler
Reto
R
Department of Pathology, CMU, Faculty of Medicine, University of Geneva, 1, rue Michel-Servet, CH 1211 Geneva 4, Switzerland.
Olleros
Maria L
ML
Vesin
Dominique
D
Parapanov
Roumen
R
Vesin
Christian
C
Kantengwa
Salomé
S
Rubbia-Brandt
Laura
L
Mensi
Noury
N
Angelillo-Scherrer
Anne
A
Martinez-Soria
Eduardo
E
Tacchini-Cottier
Fabienne
F
Garcia
Irene
I
D000818:Animals; D015850:Interleukin-6 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology; D008107:Liver Diseases / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009163:Mycobacterium bovis; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D013154:Spleen / Q000201:enzymology; D018417:Th1 Cells / Q000378:metabolism; D014376:Tuberculosis / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse