ABSTRACT
XIAP-associated factor 1 (XAF1) is an interferon (IFN)-stimulated gene (ISG) that enhances IFN-induced apoptosis. However, it is unexplored whether XAF1 is essential for the host fighting against invaded viruses. Here, we find that XAF1 is significantly upregulated in the host cells infected with emerging RNA viruses, including influenza, Zika virus (ZIKV), and SARS-CoV-2. IFN regulatory factor 1 (IRF1), a key transcription factor in immune cells, determines the induction of XAF1 during antiviral immunity. Ectopic expression of XAF1 protects host cells against various RNA viruses independent of apoptosis. Knockout of XAF1 attenuates host antiviral innate immunity in vitro and in vivo, which leads to more severe lung injuries and higher mortality in the influenza infection mouse model. XAF1 stabilizes IRF1 protein by antagonizing the CHIP-mediated degradation of IRF1, thus inducing more antiviral IRF1 target genes, including DDX58, DDX60, MX1, and OAS2. Our study has described a protective role of XAF1 in the host antiviral innate immunity against RNA viruses. We have also elucidated the molecular mechanism that IRF1 and XAF1 form a positive feedback loop to induce rapid and robust antiviral immunity. IMPORTANCE Rapid and robust induction of antiviral genes is essential for the host to clear the invaded viruses. In addition to the IRF3/7-IFN-I-STAT1 signaling axis, the XAF1-IRF1 positive feedback loop synergistically or independently drives the transcription of antiviral genes. Moreover, XAF1 is a sensitive and reliable gene that positively correlates with the viral infection, suggesting that XAF1 is a potential diagnostic marker for viral infectious diseases. In addition to the antitumor role, our study has shown that XAF1 is essential for antiviral immunity. XAF1 is not only a proapoptotic ISG, but it also stabilizes the master transcription factor IRF1 to induce antiviral genes. IRF1 directly binds to the IRF-Es of its target gene promoters and drives their transcriptions, which suggests a unique role of the XAF1-IRF1 loop in antiviral innate immunity, particularly in the host defect of IFN-I signaling such as invertebrates.
Subject(s)
Adaptor Proteins, Signal Transducing , Apoptosis Regulatory Proteins , Interferon Regulatory Factor-1 , RNA Virus Infections , RNA Viruses , Adaptor Proteins, Signal Transducing/immunology , Animals , Apoptosis Regulatory Proteins/immunology , Humans , Immunity, Innate , Interferon Regulatory Factor-1/immunology , Mice , Mice, Knockout , RNA Virus Infections/immunology , Virus ReplicationABSTRACT
A comprehensive understanding of the dynamic changes in interleukin-6 (IL-6) levels is essential for monitoring and treating patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). By analyzing the correlations between IL-6 levels and health conditions, underlying diseases, several key laboratory detection indices, and the prognosis of 1,473 patients with the coronavirus disease 2019 (COVID-19), the role of IL-6 during SARS-CoV-2 infection was demonstrated. Our results indicated that IL-6 levels were closely related to age, sex, body temperature, oxygen saturation (SpO2) of blood, and underlying diseases. As a stable indicator, the changes in IL-6 levels could indicate the inflammatory conditions during a viral infection. Two specific treatments, namely, tocilizumab and convalescent plasma therapy (CPT), decreased the level of IL-6 and relieved inflammation. CPT has an important role in the therapy for patients with critical COVID-19. We also found that patients with IL-6 levels, which were 30-fold higher than the normal level, had a poor prognosis compared to patients with lower levels of IL-6.
Subject(s)
Antibodies, Monoclonal, Humanized/therapeutic use , Antiviral Agents/therapeutic use , COVID-19 Drug Treatment , COVID-19/therapy , Interleukin-6/blood , SARS-CoV-2/genetics , Up-Regulation , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/blood , COVID-19/epidemiology , Child , China/epidemiology , Female , Humans , Immunization, Passive , Male , Middle Aged , Prognosis , Real-Time Polymerase Chain Reaction , Severity of Illness Index , Treatment Outcome , Young Adult , COVID-19 SerotherapyABSTRACT
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is wreaking havoc on public health systems worldwide. The diagnosis of COVID-19 is well defined, but efficacious treatment is lacking. There is a big gap in knowledge regarding COVID-19 patients receiving convalescent plasma transfusion (CPT), especially those also suffering from diabetes mellitus (DM). In this study, among 3059 COVID-19 patients admitted to Wuhan Huoshenshan Hospital of China, we documented the characteristics of 39 COVID-19 patients with DM receiving CPT and compared their baseline information and clinical outcomes to COVID-19 patients with DM receiving conventional treatment. We also performed the propensity-matched comparison of COVID-19 patients with DM between conventional treatment and CPT. The CPT was efficacious and beneficial for COVID-19 patients with DM, including severe or critically ill patients, without obvious adverse effects. Our data demonstrated that CPT significantly improved the clinical outcomes of COVID-19 patients with DM, especially the cure rate and duration of hospitalization compared with that in COVID-19 patients with DM receiving conventional treatment. This study not only provided a deeper understanding of characteristics in COVID-19 patients with DM receiving CPT but also highlighted the efficaciousness of CPT for COVID-19 patients with DM.