Kinetic Differences and Synergistic Antiviral Effects Between Type I and Type III Interferon Signaling Indicate Pathway Independence

Abstract

The spread of acute respiratory viral infections is controlled by type I and III interferon (IFN) signaling. While the mechanisms of type I IFN signaling have been studied in detail, features that distinguish type III IFN signaling remain poorly understood. Type III IFNs play an essential role in limiting infections of intestinal and respiratory epithelial surfaces; however, type III IFNs have been shown to activate similar genes to type I IFNs, raising the question of how these IFNs differ and their signals interact. We measured the kinetics of type I and III IFN activation, functional stability, and downstream antiviral responses on A549 human lung epithelial cells. Similar kinetics were found for transcriptional upregulation and secretion of type I and III IFNs in response to infection by an RNA virus, peaking at 12 h postinfection, and both protein types had similar stabilities with functional half-lives extending beyond 2 days. Both IFNs activated potent cellular antiviral responses; however, responses to type III IFNs were delayed by 2-6 h relative to type I IFN responses. Combined treatments with type I and III IFNs produced enhanced antiviral effects, and quantitative analysis of these data with a Bliss interaction model provides evidence for independence of type I and III IFN downstream signaling pathways. This novel synergistic interaction has therapeutic implications for treatment of respiratory virus infections.

Rapid induction and persistence of paracrine-induced cellular antiviral states arrest viral infection spread in A549 cells

“…With the aid of IFNβ and IFIT2 reporter cells we also visualized the activation of these innate immune markers in infected cells, followed by the spread of antiviral activation beyond the borders of the infected region. Activation of cellular antiviral immunity was likely due to a mixture of secreted paracrinesignaling molecules, demonstrated in this experimental system to include IFNα, IFNβ, and IFNλ 1/2/3 using ELISA (Voigt and Yin, 2015). This functional antiviral cocktail may also contain other secreted paracrine-signaling antiviral factors such as ISG15, TNFct, and IP-10 (D' Cunha et al, 1996;O'Neill and Bowie, 2010;Randall and Goodbourn, 2008;Sadler and Williams, 2008), which would function together with type I and III interferons to induce the development of cellular antiviral states.…”

“…Not only is induction of cellular antiviral states in epithelial cells after interferon treatment rapid, this effect remains potent for days to weeks after initial stimulation, independent of any other immune mechanisms. Other work suggests that these strong downstream effects may result from independent and/or synergistic interactions between multiple secreted antiviral cytokines, thus enhancing signaling effects (Voigt and Yin, 2015).…”

“…In the first 1-6 days postinfection, the predominant antiviral responses are the localized auto-and paracrine innate antiviral signaling networks involving the interferon (IFN) responses, among others (McLaren and Butchko, 1978;Miao et al, 2010). These responses consist of intracellular receptors that recognize viral factors and trigger synthesis of a set of signaling molecules including type I and III interferons (IFNs), which are secreted and signal cells, sometimes synergistically (Voigt and Yin, 2015), to enter into an antiviral state that inhibits viral replication. Antiviral states are stimulated not only in infected cells, but also in cells proximal to infection through diffusion or transport of paracrine-signaling antiviral molecules away from the infection site.…”

Respiratory syncytial virus infection induces a subset of types I and III interferons in human dendritic cells

“…Recent evidence, however, supports non-redundant functional roles for each, particularly at sub-saturating levels, which are likely more relevant to initial exposure of the respiratory mucosa to small doses of a viral pathogen contained in micro-droplets. For example, sub-saturating combinations of IFN-β and IFN-λ1 synergize towards suppression of vesicular stomatitis virus in vitro (Voigt and Yin, 2015), and additively enhance and sustain expression of many ISGs (Novatt et al, 2016). In RSV infection of MDDCs, using B18R to block type I IFNs (Figure 5), we have shown that the majority of ISG induction relies on the presence of type I IFNs, however this does not exclude the possibility that optimal ISG expression requires -α, -β and -λ IFNs in combination.…”

Interferon-Lambda: A Potent Regulator of Intestinal Viral Infections

“…While the antiviral programs induced by type I and type III IFNs exhibit substantial overlap (20)(21)(22) (Figure 1), a critical difference between the two is the cell types they affect secondary to receptor expression. The IFN-λ receptor consists of IFNLR1 and IL10Rβ.…”