Induction of iNOS expression in skeletal muscle by IL-1beta and NFkappaB activation: an in vitro and in vivo study.
OBJECTIVE
The intracellular pathway and the regulation of inducible nitric oxide synthase (iNOS) expression in skeletal muscle is incompletely understood. In vitro studies, using different cell types, suggest that inflammatory cytokines are potential triggers to induce iNOS expression.


METHODS
To analyze intracellular pathways leading to iNOS induction, rat skeletal myoblasts were incubated with inflammatory cytokines and assessed for iNOS expression by Western blot and Griess reaction. To confirm the in vitro findings, local cytokine levels were determined in skeletal muscle biopsies of patients with chronic heart failure (CHF) and correlated with iNOS expression.


RESULTS
Nitrite accumulation in the myoblast culture supernatant or iNOS protein in the cell pellet was significantly increased after incubation with IL-1beta in combination with gamma-IFN. Priming experiments revealed that gamma-IFN elevated the expression of IL-1beta receptor mRNA, whereby IL-1beta was able to induce iNOS expression. The cytokine-mediated iNOS induction was significantly reduced by blocking ERK1/ERK2 activation and completely abolished by the inhibition of NFkappaB. In skeletal muscle biopsies of CHF patients the local content of IL-1beta was significantly increased as compared to healthy controls. Furthermore, a linear correlation between IL-1beta content and iNOS expression in the skeletal muscle was detected.


CONCLUSIONS
These data demonstrate that IL-1beta, together with the priming effect of gamma-IFN, induces iNOS expression in skeletal muscle via activation of ERK1/ERK2 and NFkappaB.
Adams
Volker
V
University Leipzig-Heart Center Leipzig, Clinic of Cardiology, Germany. adav@medizin.uni-leipzig.de
Nehrhoff
Britta
B
Späte
Ulrike
U
Linke
Axel
A
Schulze
Paul C
PC
Baur
Angelika
A
Gielen
Stephan
S
Hambrecht
Rainer
R
Schuler
Gerhard
G
D000368:Aged; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D016022:Case-Control Studies; D016207:Cytokines / Q000494:pharmacology*; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006333:Heart Failure / Q000201:enzymology* / Q000276:immunology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007371:Interferon-gamma / Q000032:analysis / Q000494:pharmacology; D007375:Interleukin-1 / Q000032:analysis / Q000494:pharmacology; D008297:Male; D048053:Mitogen-Activated Protein Kinase 6; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000276:immunology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D011392:Proline / Q000031:analogs & derivatives* / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction; D013859:Thiocarbamates / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D000975:Antioxidants; D016207:Cytokines; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007375:Interleukin-1; D016328:NF-kappa B; D011725:Pyridines; D013859:Thiocarbamates; D014409:Tumor Necrosis Factor-alpha; C066229:prolinedithiocarbamate; D007371:Interferon-gamma; D011392:Proline; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D048053:Mitogen-Activated Protein Kinase 6; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one