Article Text
Abstract
Background and aim: Activated myofibroblast-like cells, originating from hepatic stellate cells (HSC/MFs) or other cellular sources, play a key profibrogenic role in chronic liver diseases (CLDs) that, as suggested by studies in animal models or rat HSC/MFs, may be modulated by reactive oxygen intermediates (ROI). In this study, human HSC/MFs, exposed to different levels of superoxide anion (O2•−) and, for comparison, hydrogen peroxide (H2O2), were analysed in terms of cytotoxicity, proliferative response, and migration.
Methods: Cultured human HSC/MFs were exposed to controlled O2•− generation by hypoxanthine/xanthine oxidase systems or to a range of H2O2 concentrations. Induction of cell death, proliferation, and migration were investigated using morphology, molecular biology, and biochemical techniques.
Results: Human HSC/MFs were shown to be extremely resistant to induction of cell death by O2•− and only high rates of O2•− generation induced either necrotic or apoptotic cell death. Non-cytotoxic low levels of O2•−, able to upregulate procollagen type I expression (but not tissue inhibitor of metalloproteinase 1 and 2), stimulated migration of human HSC/MFs in a Ras/extracellular regulated kinase (ERK) dependent, antioxidant sensitive way, without affecting basal or platelet derived growth factor (PDGF) stimulated cell proliferation. Non-cytotoxic levels of H2O2 did not affect Ras/ERK or proliferative response. A high rate of O2•− generation or elevated levels of H2O2 induced cytoskeletal alterations, block in motility, and inhibition of PDGF dependent DNA synthesis.
Conclusions: Low non-cytotoxic levels of extracellularly generated O2•− may stimulate selected profibrogenic responses in human HSC/MFs without affecting proliferation.
- CLDs, chronic liver diseases
- ECM, extracellular matrix
- MFs, myofibroblast-like cells
- HSC, hepatic stellate cells
- HSC/MFs, activated hepatic stellate cells in myofibroblast-like phenotype
- ROI, reactive oxygen intermediates
- O2•−, superoxide anion
- H2O2, hydrogen peroxide
- HNE, 4-hydroxynonenal
- TIMP, tissue inhibitor of metalloproteinases
- PDGF, platelet derived growth factor
- TGF-β1, transforming growth factor β1
- ECL, enhanced chemiluminescence
- SFI medium, serum free Iscove’s medium
- NO, nitric oxide
- L-NAME, Nω-nitro-L-arginine methyl ester
- LDH, lactate dehydrogenase
- X/XO, hypoxanthine/xanthine oxidase system generating superoxide anion
- SOD, superoxide dismutase
- ERK, extracellular regulated kinase
- PI-3 K, phosphatidyl inositol 3-kinase
- activated human hepatic stellate cells
- liver fibrosis
- superoxide anion
- myofibroblast migration
- induction of cell death
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- CLDs, chronic liver diseases
- ECM, extracellular matrix
- MFs, myofibroblast-like cells
- HSC, hepatic stellate cells
- HSC/MFs, activated hepatic stellate cells in myofibroblast-like phenotype
- ROI, reactive oxygen intermediates
- O2•−, superoxide anion
- H2O2, hydrogen peroxide
- HNE, 4-hydroxynonenal
- TIMP, tissue inhibitor of metalloproteinases
- PDGF, platelet derived growth factor
- TGF-β1, transforming growth factor β1
- ECL, enhanced chemiluminescence
- SFI medium, serum free Iscove’s medium
- NO, nitric oxide
- L-NAME, Nω-nitro-L-arginine methyl ester
- LDH, lactate dehydrogenase
- X/XO, hypoxanthine/xanthine oxidase system generating superoxide anion
- SOD, superoxide dismutase
- ERK, extracellular regulated kinase
- PI-3 K, phosphatidyl inositol 3-kinase
Footnotes
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Conflict of interest: None declared.