Hepatotropic growth factors protect hepatocytes during inflammation by upregulation of antioxidative systems

Abstract

To investigate effects of hepatotropic growth factors on radical production in rat hepatocytes during sepsis. Rat hepatocytes, isolated by collagenase perfusion, were incubated with a lipopolysaccharide (LPS)-containing cytokine mixture of interleukin-1β, tumor necrosis factor-α and interferon-γ to simulate sepsis and either co-incubated or pre-incubated with hepatotropic growth factors, e.g. hepatocyte growth factor, epidermal growth factor and/or transforming growth factor-α. Cells were analyzed for glutathione levels. Culture supernatants were assayed for production of reactive oxygen intermediates (ROIs) as well as NO(2) (-), NO(3) (-) and S-nitrosothiols. To determine cellular damage, release of aspartate aminotransferase (AST) into the culture medium was analyzed. Activation of nuclear factor (NF)-κB was measured by electrophoretic mobility shift assay. Rat hepatocytes treated with the LPS-containing cytokine mixture showed a significant increase in ROI and nitrogen oxide intermediate formation. AST leakage was not significantly increased in cells treated with the LPS-containing cytokine mixture, independent of growth-factor co-stimulation. However, pretreatment with growth factors significantly reduced AST leakage and ROI formation while increasing cellular glutathione. Application of growth factors did not result in increased NF-κB activation. Pretreatment with growth factors further increased formation of NO(2) (-), NO(3) (-) and S-nitrosothiols in hepatocytes stimulated with LPS-containing cytokine mixture. Thus, we propose that, together with an increase in glutathione increased NO(2) (-), NO(3) (-) formation might shift their metabolism towards non-toxic products. Our data suggest that hepatotropic growth factors positively influence sepsis-induced hepatocellular injury by reducing cytotoxic ROI formation via induction of the cellular protective antioxidative systems.