Pegylated IFN-α regulates hepatic gene expression through transient Jak/STAT activation
Michael T. Dill, Zuzanna Makowska, Gaia Trincucci, Andreas J. Gruber, Julia E. Vogt, Magdalena Filipowicz, Diego Calabrese, Ilona Krol, Daryl T. Lau, Luigi Terracciano, Erik van Nimwegen, Volker Roth, Markus H. Heim
Michael T. Dill, Zuzanna Makowska, Gaia Trincucci, Andreas J. Gruber, Julia E. Vogt, Magdalena Filipowicz, Diego Calabrese, Ilona Krol, Daryl T. Lau, Luigi Terracciano, Erik van Nimwegen, Volker Roth, Markus H. Heim
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Research Article Immunology

Pegylated IFN-α regulates hepatic gene expression through transient Jak/STAT activation

Abstract

The use of pegylated interferon-α (pegIFN-α) has replaced unmodified recombinant IFN-α for the treatment of chronic viral hepatitis. While the superior antiviral efficacy of pegIFN-α is generally attributed to improved pharmacokinetic properties, the pharmacodynamic effects of pegIFN-α in the liver have not been studied. Here, we analyzed pegIFN-α–induced signaling and gene regulation in paired liver biopsies obtained prior to treatment and during the first week following pegIFN-α injection in 18 patients with chronic hepatitis C. Despite sustained high concentrations of pegIFN-α in serum, the Jak/STAT pathway was activated in hepatocytes only on the first day after pegIFN-α administration. Evaluation of liver biopsies revealed that pegIFN-α induces hundreds of genes that can be classified into four clusters based on different temporal expression profiles. In all clusters, gene transcription was mainly driven by IFN-stimulated gene factor 3 (ISGF3). Compared with conventional IFN-α therapy, pegIFN-α induced a broader spectrum of gene expression, including many genes involved in cellular immunity. IFN-induced secondary transcription factors did not result in additional waves of gene expression. Our data indicate that the superior antiviral efficacy of pegIFN-α is not the result of prolonged Jak/STAT pathway activation in hepatocytes, but rather is due to induction of additional genes that are involved in cellular immune responses.

Authors

Michael T. Dill, Zuzanna Makowska, Gaia Trincucci, Andreas J. Gruber, Julia E. Vogt, Magdalena Filipowicz, Diego Calabrese, Ilona Krol, Daryl T. Lau, Luigi Terracciano, Erik van Nimwegen, Volker Roth, Markus H. Heim

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Figure 7

U-STAT1 does not induce ISGs.

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U-STAT1 does not induce ISGs. (A) Three clones with different expression...
(A) Three clones with different expression levels of WT (WT cl1, WT cl2, and WT cl3) or mutated STAT1 (Y701F cl1, Y701F cl2, and Y701F cl3) were stimulated with IFN-α. STAT1-deficient U3A cells and STAT1 WT parental 2fTGH cells were used as controls. IFN-α induced STAT1 phosphorylation in 2fTGH and in all three WT clones. Actin is shown as a loading control. The cells were either untreated or treated for 15 minutes with 1,000 U/ml of IFN-α. WT cl1 and Y701F cl1 express STAT1 in an amount similar to that induced by 2fTGH cells treated for 24 hours with 1,000 U/ml of IFN-α. Shown are representative blots each from three independently performed experiments (black lanes separate blots that were derived from the same gel, but were noncontiguous). (B) IFN-α–induced OAS1 mRNA expression relative to GAPDH was assessed by qRT-PCR. Cells were treated with 1,000 U/ml IFN-α for 8 hours. Upregulation of OAS1 was found only in cells with WT STAT1 after IFN-α treatment. Expression of maximal amounts of Y701F-mutated STAT1 in U3A cells did not induce ISG expression. Shown are the mean values with SEM of three replicate experiments.