Interferons (IFNs) are widely used in treating coronavirus disease 2019 (COVID-19) patients. However, a recent report of ACE2, the host factor mediating SARS-Cov-2 infection, identifying it as interferon-stimulated raised considerable safety concern. To examine the association between the use and timing of IFN-α2b and clinical outcomes, we analyzed in a retrospective multicenter cohort study of 446 COVID-19 patients in Hubei, China. Regression models estimated that early administration (≤5 days after admission) of IFN-α2b was associated with reduced in-hospital mortality in comparison with no admission of IFN-α2b, whereas late administration of IFN-α2b was associated with increased mortality. Among survivors, early IFN-α2b was not associated with hospital discharge or computed tomography (CT) scan improvement, whereas late IFN-α2b was associated with delayed recovery. Additionally, early IFN-α2b and umifenovir alone or together were associated with reduced mortality and accelerated recovery in comparison with treatment with lopinavir/ritonavir (LPV/r) alone. We concluded that administration of IFN-α2b during the early stage of COVID-19 could induce favorable clinical responses.
Interferon regulatory factor (IRF) family members, especially interferon regulatory factor-1 (IRF-1) and interferon regulatory factor-8 (IRF-8 or ICSBP), play important roles in interferon signaling in a wide range of host responses to infection and tumor growth. Interleukin-27 (IL-27), as a member of the IL-12 cytokine family, not only acts as a proinflammatory cytokine that regulates the differentiation of naive T helper cells but also possesses anti-inflammatory properties. IL-27 consists of EBI3 (Epstein-Barr virus-induced gene 3) and p28 subunits. Our previous work has shown that IRF-1 regulates IL-27 p28 gene transcription by specifically binding to the IRF-1 response element in the p28 promoter. In this study, we found that IRF-8-deficient macrophages were highly defective in the production of IL-27 p28 at both mRNA and protein levels. Circulating IL-27 p28 in serum was also decreased in IRF-8 ؊/؊ mice in a septic shock model. Lipopolysaccharide, as a potent inducer of IL-27 p28 expression, could activate IRF-8 expression in a MyD88-dependent pathway, which in turn induced p28 gene transcription through NF-B and/or IRF-8. Transcriptional analyses revealed that IRF-8 activated p28 gene transcription through binding to a site located at ؊57 to ؊48 in the p28 promoter overlapping the IRF-1 binding site. Consistent with this observation, overexpression of both IRF-8 and IRF-1 additively activated IL-27 p28 promoter. This study provides further mechanistic information regarding how signals initiated during innate and adaptive immune responses synergize to yield greater IL-27 production and sustained cellular immunity.
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