Kinetic differences in the induction of interferon stimulated genes by interferon-α and interleukin 28B are altered by infection with hepatitis C virus

Abstract

Several genome-wide association studies (GWAS) have identified a genetic polymorphism associated with the gene locus for interleukin 28B (IL28B), a type III interferon (IFN), as a major predictor of clinical outcome in hepatitis C. Antiviral effects of the type III IFN family have previously been shown against several viruses, including hepatitis C virus (HCV), and resemble the function of type I IFN including utilization of the intracellular JAK-STAT pathway. Effects unique to IL28B that would distinguish it from IFN-α are not well defined. By analyzing the transcriptomes of primary human hepatocytes (PHH) treated with IFN-α or IL28B, we sought to identify functional differences between IFN-α and IL28B to better understand the roles of these cytokines in the innate immune response. Although our data did not reveal distinct gene signatures, we detected striking kinetic differences between IFN-α and IL28B stimulation for interferon stimulated genes (ISGs). While gene induction was rapid and peaked at 8 h of stimulation with IFN-α in PHH, IL28B produced a slower, but more sustained increase in gene expression. We confirmed these findings in the human hepatoma cell line Huh7.5.1. Interestingly, in HCV infected cells, the rapid response after stimulation with IFN-α was blunted, and the induction pattern resembled that caused by IL28B. In conclusion, we describe the kinetics of gene induction as being fundamentally different for stimulations with either IFN-α or IL28B in hepatocytes suggesting distinct roles of these cytokines within the immune response. Furthermore, we demonstrate that the observed differences are substantially altered by infection with the hepatitis C virus.

IFN‐λ‐mediated IL‐12 production in macrophages induces IFN‐γ production in human NK cells

“…In contrast, the restricted expression of IFN-λR1 prevented a direct action of IFN-λ on both NK cells and monocytes, with only responses observed on differentiated macrophages. This suggests that IFN-λ might play a more prominent role in tissue-specific responses as compared to the periphery, in line with other studies describing that IFN-λ1 has a more delayed and prolonged effect through activation of specific tissue-resident cells, specifically epithelial cells and hepatocytes [25,26]. TLR-dependent crosstalk between NK cells and macrophages has already been described in tissue-specific interactions in the liver.…”

“…At present, it is unclear how triggering of similar signaling pathways by IFN-α and IFN-λ results in divergent biological activities. Besides macrophages, further functional differences have been described between IFN-α and IFN-λ in their modulation of hepatocytes, where IFN-λ has been shown to activate a more restricted subset of cells as well as induce sustained interferon-stimulated gene responses [25,26].To further define a role for IFN-λ in antiviral immune responses, the goal of this study was to determine whether IFN-λ could exert any immunomodulatory effects on NK cells, and if so, how that response compared to the action of type I IFNs. A previous study had described IFN-λ as being able to partially inhibit NK-cell-derived IFN-γ production upon IL-12/15 stimulation [27,28], but an effect of IFN-λ on NK cells could not be reproduced in an ensuing response to the original article [29].…”

Type I and type III interferon-induced immune response: It's a matter of kinetics and magnitude

“…In an attempt to investigate the molecular factors and the signaling elements contributing to the peculiar kinetics of ISG response in IFN-a-stimulated hepatocytes, Bolen et observed after IFN-a treatment was altered by hepatitis C virus (HCV) infection. 12 Taken together with a previous study reporting that combinations of IL-29 with type I IFN induce greater antiviral activity against HCV than individual cytokines alone, 17 the observation that HCV dampens early IFN-a-induced ISG response reveals an obvious complementary role for IFN-a and IL-28B in mounting an appropriate antiviral response against this flavivirus in hepatocytes.…”

“…Both studies reach a similar, but somewhat unpredicted, conclusion that type I and III IFNs stimulate similar sets of ISGs, albeit with very distinct kinetics of response and magnitude of stimulation. 11,12 These two parallel studies from Bolen et al and Jilg et al converge on an answer that contrasts with studies demonstrating that type I and III IFNs induce both overlapping and distinct sets of genes. 8,13,14 In the current experiments, transcriptome analysis from human hepatoma Huh7 cells or primary human hepatocytes (PHHs) stimulated with comparable concentrations of IFN-a, -b, -k1, -k2, or -k3 revealed a hierarchy of gene expression, with IFN-b identified as the most biologically active cytokine, followed by IFN-a and IFN-ks ( Fig.…”

“…16 The studies also intriguingly reported on a unique kinetic profile of ISG expression in IFN-a-treated Huh7 or PHHs. 11,12 Indeed, both IFN-b and IFN-k triggered a sustained ISG response; on the other hand, IFN-a produced a kinetic profile of genes that peaked at early times of treatment and then rapidly decreased (Fig. 1).…”