Dynamic expression profiling of type I and type III interferon-stimulated hepatocytes reveals a stable hierarchy of gene expression.
Despite activating similar signaling cascades, the type I and type III interferons (IFNs) differ in their ability to antagonize virus replication. However, it is not clear whether these cytokines induce unique antiviral states, particularly in the liver, where the clinically important hepatitis B and C viruses cause persistent infection. Here, clustering and promoter analyses of microarray-based gene expression profiling were combined with mechanistic studies of signaling pathways to dynamically characterize the transcriptional responses induced by these cytokines in Huh7 hepatoma cells and primary human hepatocytes. Type I and III IFNs differed greatly in their level of interferon-stimulated gene (ISG) induction with a clearly detectable hierarchy (IFN-β > IFN-α > IFN-λ3 > IFN-λ1 > IFN-λ2). Notably, although the hierarchy identified varying numbers of differentially expressed genes when quantified using common statistical thresholds, further analysis of gene expression over multiple timepoints indicated that the individual IFNs do not in fact regulate unique sets of genes. The kinetic profiles of IFN-induced gene expression were also qualitatively similar with the important exception of IFN-α. While stimulation with either IFN-β or IFN-λs resulted in a similar long-lasting ISG induction, IFN-α signaling peaked early after stimulation then declined due to a negative feedback mechanism. The quantitative expression hierarchy and unique kinetics of IFN-α reveal potential specific roles for individual IFNs in the immune response, and elucidate the mechanism behind previously observed differences in IFN antiviral activity. While current clinical trials are focused on IFN-λ1 as a potential antiviral therapy, the finding that IFN-λ3 invariably possesses the highest activity among type III IFNs suggests that this cytokine may have superior clinical activity.
Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT.
Christopher R
CR
Bolen
Siyuan
S
Ding
Michael D
MD
Robek
Steven H
SH
Kleinstein
D045744:Cell Line, Tumor; D005246:Feedback; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D007372:Interferons; D007378:Interleukins / Q000494:pharmacology; D010766:Phosphorylation; D050794:STAT1 Transcription Factor / Q000378:metabolism; D013997:Time Factors; D000095022:Interferon Lambda
D007370:Interferon Type I; D007372:Interferons; D007378:Interleukins; D050794:STAT1 Transcription Factor; C000624353:interferon-lambda, human; D000095022:Interferon Lambda; C494079:STAT1 protein, human