Antiviral Activity of Type I, II, and III Interferons Counterbalances ACE2 Inducibility and Restricts SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), is a recently emerged respiratory coronavirus that has infected >23 million people worldwide with >800,000 deaths. Few COVID-19 therapeutics are available, and the basis for severe infections is poorly understood. Here, we investigated properties of type I (ß), II (γ), and III (λ1) interferons (IFNs), potent immune cytokines that are normally produced during infection and that upregulate IFN-stimulated gene (ISG) effectors to limit virus replication. IFNs are already in clinical trials to treat COVID-19. However, recent studies highlight the potential for IFNs to enhance expression of host angiotensin-converting enzyme 2 (ACE2), suggesting that IFN therapy or natural coinfections could exacerbate COVID-19 by upregulating this critical virus entry receptor. Using a cell line model, we found that beta interferon (IFN-ß) strongly upregulated expression of canonical antiviral ISGs, as well as ACE2 at the mRNA and cell surface protein levels. Strikingly, IFN-λ1 upregulated antiviral ISGs, but ACE2 mRNA was only marginally elevated and did not lead to detectably increased ACE2 protein at the cell surface. IFN-γ induced the weakest ISG response but clearly enhanced surface expression of ACE2. Importantly, all IFN types inhibited SARS-CoV-2 replication in a dose-dependent manner, and IFN-ß and IFN-λ1 exhibited potent antiviral activity in primary human bronchial epithelial cells. Our data imply that type-specific mechanisms or kinetics shape IFN-enhanced ACE2 transcript and cell surface levels but that the antiviral action of IFNs against SARS-CoV-2 counterbalances any proviral effects of ACE2 induction. These insights should aid in evaluating the benefits of specific IFNs, particularly IFN-λ, as repurposed therapeutics.IMPORTANCE Repurposing existing, clinically approved, antiviral drugs as COVID-19 therapeutics is a rapid way to help combat the SARS-CoV-2 pandemic. Interferons (IFNs) usually form part of the body's natural innate immune defenses against viruses, and they have been used with partial success to treat previous new viral threats, such as HIV, hepatitis C virus, and Ebola virus. Nevertheless, IFNs can have undesirable side effects, and recent reports indicate that IFNs upregulate the expression of host ACE2 (a critical entry receptor for SARS-CoV-2), raising the possibility that IFN treatments could exacerbate COVID-19. Here, we studied the antiviral- and ACE2-inducing properties of different IFN types in both a human lung cell line model and primary human bronchial epithelial cells. We observed differences between IFNs with respect to their induction of antiviral genes and abilities to enhance the cell surface expression of ACE2. Nevertheless, all the IFNs limited SARS-CoV-2 replication, suggesting that their antiviral actions can counterbalance increased ACE2.

Evaluation of safety, efficacy, tolerability, and treatment-related outcomes of type I interferons for human coronaviruses (HCoVs) infection in clinical practice: An updated critical systematic review and meta-analysis.

BACKGROUND: There is no vaccine or specific antiviral treatment for HCoVs infection. The use of type I interferons for coronavirus is still under great debate in clinical practice. MATERIALS AND METHODS: A literature search of all relevant studies published on PubMed, Cochrane library, Web of Science database, Science Direct, Wanfang Data, and China National Knowledge Infrastructure (CNKI) until February 2020 was performed. RESULTS: Of the 1081 identified articles, only 15 studies were included in the final analysis. Comorbidities and delay in diagnosis were significantly associated with case mortality. Type I interferons seem to improve respiratory distress, relieve lung abnormalities, present better saturation, reduce needs for supplemental oxygen support. Type I interferons seem to be well tolerated, and don't increase life threating adverse effects. Data on IFNs in HCoVs are limited, heterogenous and mainly observational. CONCLUSIONS: Current data do not allow making regarding robust commendations for the use of IFNs in HCoVs in general or in specific subtype. But we still recommend type I interferons serving as first-line antivirals in HCoVs infections within local protocols, and interferons may be adopted to the treatments of the SARS-CoV-2 as well. Well-designed large-scale prospective randomized control trials are greatly needed to provide more robust evidence on this topic.