Effect of tumour necrosis factor-alpha on proliferation, activation and protein synthesis of rat hepatic stellate cells

Background/Aims: Hepatic stellate cells represent the principal matrix-synthesising cells of damaged liver and are targets of a number of cytokines currently under investigation, The study analyses the effects of tumour necrosis factor-alpha and interferon-gamma on proliferation, ''activation'' and protein synthesis of hepatic stellate cells. Methods: Primary cultures of hepatic stellate cells were exposed to tumour necrosis factor-alpha and interferon-gamma. Cell proliferation was studied by H-3-thymidine and bromo-deoxy-uridine incorporation. Protein synthesis was analysed using immunoprecipitation, Western- and Northern blotting techniques. Results: Proliferation of hepatic stellate cells was reduced by tumor necrosis factor-alpha and interferon-gamma, while ''activation'' of hepatic stellate cells as assessed by expression of smooth muscle alpha-actin and of TGF-beta/activin type I receptor was induced by tumour necrosis factor-alpha but downregulated by interferon-gamma, Tumour necrosis factor-alpha increased the synthesis of distinct extracellular matrix proteins, particularly of fibronectin and tenascin, but decreased collagen type In expression, In contrast, interferon-gamma reduced the synthesis of all connective tissue proteins tested, Among the protease inhibitors, interferon-gamma induced C1-esterase inhibitor synthesis, while tumour necrosis factor-alpha stimulated plasminogen activator inhibitor type 1 production. Conclusions: Tumour necrosis factor-alpha and interferon-gamma decrease proliferation of hepatic stellate cells, while ''activation'' of hepatic stellate cells and synthesis of proteins involved in matrix metabolism are regulated in a differential, cytokine-specific manner, suggesting that both cytokines play an important role in liver repair.