Cyclophilin inhibitors restrict Middle East respiratory syndrome coronavirus<i>via</i>interferon-λ<i>in vitro</i>and in mice
Lucie Sauerhering, Alexandra Kupke, Lars Meier, Erik Dietzel, Judith Hoppe, Achim D. Gruber, Stefan Gattenloehner, Biruta Witte, Ludger Fink, Nina Hofmann, Tobias Zimmermann, Alexander Goesmann, Andrea Nist, Thorsten Stiewe, Stephan Becker, Susanne Herold, Christin Peteranderl
Abstract
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. 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. Calu-3 cells and primary human alveolar epithelial cells (hAECs) were infected with MERS-CoV and treated with CsA or ALV or inhibitors targeting cyclophilin inhibitor-regulated molecules including calcineurin, nuclear factor of activated T-cells (NFATs) or mitogen-activated protein kinases. Novel CsA-induced pathways were identified by RNA sequencing and manipulated by gene knockdown or neutralising antibodies. Viral replication was quantified by quantitative real-time PCR and 50% tissue culture infective dose. Data were validated in a murine MERS-CoV infection model. Both CsA and ALV reduced MERS-CoV titres and viral RNA replication in Calu-3 cells and hAECs, 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. Downregulation of IRF1 or IFNλ increased MERS-CoV propagation in the presence of CsA. Importantly, oral application of CsA reduced MERS-CoV replication in vivo , correlating with elevated lung IFNλ levels and improved outcome. 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 for treating MERS-CoV infection.