Antiviral cytokines induce hepatic expression of the granzyme B inhibitors, proteinase inhibitor 9 and serine proteinase inhibitor 6.
Expression of the granzyme B inhibitors, human proteinase inhibitor 9 (PI-9), or the murine orthologue, serine proteinase inhibitor 6 (SPI-6), confers resistance to CTL or NK killing by perforin- and granzyme-dependent effector mechanisms. In light of prior studies indicating that virally infected hepatocytes are selectively resistant to this CTL effector mechanism, the present studies investigated PI-9 and SPI-6 expression in hepatocytes and hepatoma cells in response to adenoviral infection and to cytokines produced during antiviral immune responses. Neither PI-9 nor SPI-6 expression was detected by immunoblotting in uninfected murine or human hepatocytes. Similarly, human Huh-7 hepatoma cells were found to express only very low levels of PI-9 relative to levels detected in perforin- and granzyme-resistant CTL or lymphokine-activated killer cells. Following in vivo adenoviral infection or in vitro culture with IFN-alphabeta or IFN-gamma, SPI-6 expression was induced in murine hepatocytes. Similarly, after culture with IFN-alpha, induction of PI-9 mRNA and protein expression was observed in human hepatocytes and Huh-7 cells. IFN-gamma and TNF-alpha also induced 4- to 10-fold higher levels of PI-9 mRNA expression in Huh-7 cells, whereas levels of mRNA encoding a related serine proteinase inhibitor, proteinase inhibitor 8, were unaffected by culture of Huh-7 cells with IFN-alpha, IFN-gamma, or TNF-alpha. These findings indicate that cytokines that promote antiviral cytopathic responses also regulate expression of the cytoprotective molecules, PI-9 and SPI-6, in hepatocytes that are potential targets of CTL and NK effector mechanisms.
Barrie
Mahmoud B
MB
Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Stout
Heather W
HW
Abougergi
Marwan S
MS
Miller
Bonnie C
BC
Thiele
Dwain L
DL
D000257:Adenoviridae Infections / Q000201:enzymology / Q000276:immunology; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000276:immunology / Q000821:virology; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D003601:Cytotoxicity Tests, Immunologic; D053804:Granzymes; D022781:Hepatocytes / Q000201:enzymology* / Q000276:immunology* / Q000821:virology; D006801:Humans; D007113:Immunity, Innate; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D018345:Mice, Knockout; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology; D015843:Serpins / Q000096:biosynthesis*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000998:Antiviral Agents; D016207:Cytokines; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; C102316:SERPINB9 protein, human; D015843:Serpins; C094472:serpin B6; D054353:Perforin; C509213:GZMB protein, human; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases