Type I and Type II interferon signaling pathways (IFN-I/II pathways)

The Type I and Type II interferon (IFN) pathways are essential components of the mammalian immune system, coordinating the cellular response to viral infections and malignant transformation (Ivashkiv & Donlin, 2014). Type I IFNs (e.g., IFN-α and IFN-β) bind to the heterodimeric IFNAR1/IFNAR2 receptor, triggering the activation of JAK1 and TYK2 kinases, which subsequently phosphorylate STAT1 and STAT2 to form the ISGF3 transcription factor complex (Platanias, 2005). This complex translocates to the nucleus to induce the expression of hundreds of interferon-stimulated genes (ISGs), such as MX1, OAS1, and PKR, which directly inhibit viral replication and protein synthesis (Schoggins, 2019). Type II IFN (IFN-γ) signals through the IFNGR1/IFNGR2 complex, primarily activating JAK1 and JAK2 to form STAT1 homodimers that promote macrophage activation and MHC class II expression (Ivashkiv, 2018). These pathways are major therapeutic targets: recombinant IFNs are used as antiviral and antineoplastic agents, while inhibitors like JAK inhibitors and anti-IFNAR antibodies (e.g., anifrolumab) are employed to treat autoimmune conditions like systemic lupus erythematosus where interferon signaling is pathologically elevated (Crow, 2014). However, modulating these pathways requires careful management due to side effects such as flu-like symptoms, hematologic toxicities, and the risk of secondary infections (Borden et al., 2007).

Other names

Interferon signaling cascadeJAK-STAT interferon axisType I and II IFN pathwaysAntiviral interferon response

Agonism of interferon receptors (IFNAR/IFNGR), inhibition of Janus kinases (JAK1/JAK2/TYK2), and monoclonal antibody-mediated blockade of interferon receptors.