Abstract
Rationale While severe coronavirus infections, including Middle East respiratory syndrome coronavirus (MERS-CoV) cause lung injury with high mortality rates, protective treatment strategies are not approved for clinical use.
Objectives We elucidated the molecular mechanisms by which the cyclophilin inhibitors Cyclosporin A (CsA) and Alisporivir (ALV) restrict MERS-CoV to validate their suitability as readily-available therapy in MERS-CoV infection.
Methods Calu-3 cells and primary human alveolar epithelial cells (hAEC) were infected with MERS-CoV and treated with CsA or ALV or inhibitors targeting cyclophilin inhibitor-regulated molecules including Calcineurin, NFAT, or MAP kinases. Novel CsA-induced pathways were identified by RNA sequencing and manipulated by gene knockdown or neutralising antibodies. Viral replication was quantified by qRT-PCR and TCID50. Data were validated in a murine MERS-CoV infection model.
Results CsA and ALV both reduced MERS-CoV titers and viral RNA replication in Calu-3 and hAEC improving epithelial integrity. While neither Calcineurin nor NFAT inhibition reduced MERS-CoV propagation, blockade of c-Jun N-terminal kinase diminished infectious viral particle release but not RNA accumulation. Importantly, CsA induced interferon regulatory factor 1 (IRF1), a pronounced type-III-interferon (IFNλ) response and expression of antiviral genes. Down-regulation of IRF1 or IFNλ increased MERS-CoV propagation in presence of CsA. Importantly, oral application of CsA reduced MERS-CoV replication in vivo, correlating with elevated lung IFNλ levels and improved outcome.
Conclusions We provide evidence that cyclophilin inhibitors efficiently decrease MERS-CoV replication in vitro and in vivo via upregulation of inflammatory, antiviral cell responses, in particular IFNλ. CsA might therefore represent a promising candidate to treat MERS-CoV infection.
Abstract
The cyclophilin inhibitors Cyclosporin A and Alisporivir activate host innate immunity by induction of interferon lambda via activation of IRF1 in human lung epithelial cells and in vivo, resulting in a significant inhibition of MERS-CoV.
Footnotes
Sequencing data are available at Array Express, accession number E-MTAB-8222.
This article has supplementary material available from erj.ersjournals.com
Support statement: This work was supported by the German Research Foundation (KFO309 P2/P8; Project ID: 284237345; SFB-TR84 B2, Project ID: 114933180; SFB1021 C05, Project ID: 197785619), by the German Center for Lung Research (DZL), by the German Center for Infection Research (DZIF) and the Cardio-Pulmonary Institute (CPI), EXC 2026, Project ID: 390649896. Cardio-Pulmonary Institute (CPI); Grant: EXC 2026, Project ID: 390649896; Deutsche Forschungsgemeinschaft; DOI: http://dx.doi.org/10.13039/501100001659; Grant: Project ID: 114933180 B2, Project ID: 197785619 C05, Project ID: 284237345 P2/8; Deutsches Zentrum für Infektionsforschung; DOI: http://dx.doi.org/10.13039/100009139; Deutsche Zentrum für Lungenforschung; DOI: http://dx.doi.org/10.13039/501100010564.
Conflict of interest: Dr. Sauerhering has nothing to disclose.
Conflict of interest: Dr. Kupke has nothing to disclose.
Conflict of interest: Dr. Meier has nothing to disclose.
Conflict of interest: Dr. Dietzel has nothing to disclose.
Conflict of interest: Judith Hoppe has nothing to disclose.
Conflict of interest: Dr. Gruber has nothing to disclose.
Conflict of interest: Dr. Gattenloehner has nothing to disclose.
Conflict of interest: Dr. Witte has nothing to disclose.
Conflict of interest: Dr. Fink has nothing to disclose.
Conflict of interest: Nina Hofmann has nothing to disclose.
Conflict of interest: Dr. Zimmermann has nothing to disclose.
Conflict of interest: Dr. Goesmann has nothing to disclose.
Conflict of interest: Dr. Nist has nothing to disclose.
Conflict of interest: Dr. Stiewe has nothing to disclose.
Conflict of interest: Dr. Becker has nothing to disclose.
Conflict of interest: Dr. Herold has nothing to disclose.
Conflict of interest: Dr. Peteranderl has nothing to disclose.
- Received September 16, 2019.
- Accepted June 3, 2020.
- Copyright ©ERS 2020
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