LAUSR

The SARS-CoV-2 pandemic has emphasized the need to understand the mechanisms of severe lung inflammatory pathology caused by human deadly coronaviruses in order to design new antiviral therapies. Here, we identify miRNA-223-3p as a host miRNA involved in the regulation of lung inflammatory response mediated by envelope (E) protein during SARS-CoV infection. miRNAs downregulate the expression of cellular mRNAs and participate in complex networks of mRNA–miRNA interactions that regulate cellular processes. ABSTRACT Severe acute respiratory syndrome coronavirus (SARS-CoV) and the closely related SARS-CoV-2 are emergent highly pathogenic human respiratory viruses causing acute lethal disease associated with lung damage and dysregulated inflammatory responses. SARS-CoV envelope protein (E) is a virulence factor involved in the activation of various inflammatory pathways. Here, we study the contribution of host miRNAs to the virulence mediated by E protein. Small RNAseq analysis of infected mouse lungs identified miRNA-223 as a potential regulator of pulmonary inflammation, since it was significantly increased in SARS-CoV-WT virulent infection compared to the attenuated SARS-CoV-ΔE infection. In vivo inhibition of miRNA-223-3p increased mRNA levels of pro-inflammatory cytokines and NLRP3 inflammasome, suggesting that during lung infection, miRNA-223 might contribute to restrict an excessive inflammatory response. Interestingly, miRNA-223-3p inhibition also increased the levels of the CFTR transporter, which is involved in edema resolution and was significantly downregulated in the lungs of mice infected with the virulent SARS-CoV-WT virus. At the histopathological level, a decrease in the pulmonary edema was observed when miR-223-3p was inhibited, suggesting that miRNA-223-3p was involved in the regulation of the SARS-CoV-induced inflammatory pathology. These results indicate that miRNA-223 participates in the regulation of E protein-mediated inflammatory response during SARS-CoV infection by targeting different host mRNAs involved in the pulmonary inflammation, and identify miRNA-223 as a potential therapeutic target in SARS-CoV infection. IMPORTANCE The SARS-CoV-2 pandemic has emphasized the need to understand the mechanisms of severe lung inflammatory pathology caused by human deadly coronaviruses in order to design new antiviral therapies. Here, we identify miRNA-223-3p as a host miRNA involved in the regulation of lung inflammatory response mediated by envelope (E) protein during SARS-CoV infection. miRNAs downregulate the expression of cellular mRNAs and participate in complex networks of mRNA–miRNA interactions that regulate cellular processes. The inhibition of miRNA-223 in infected mice by intranasal administration of antisense RNAs led to changes in the expression of host factors involved in inflammation (cytokines, chemokines, and NLRP3 inflammasome) and in the resolution of lung edema ion transporter CFTR. These results confirmed the contribution of miRNA-223 to the regulation of SARS-CoV-induced pathogenic processes and support the therapeutic potential of inhibiting miRNAs during coronavirus infection using RNA interference approaches.