SARS-CoV-2 Nsp2 Contributes to Inflammation by Activating NF-κB

COVID-19 is associated with robust inflammation and partially impaired antiviral responses. The modulation of inflammatory gene expression by SARS-CoV-2 is not completely understood. In this study, we characterized the inflammatory and antiviral responses mounted during SARS-CoV-2 infection. K18-hACE2 mice were infected with a Wuhan-like strain of SARS-CoV-2, and the transcriptional and translational expression interferons (IFNs), cytokines, and chemokines were analyzed in mouse lung homogenates. Our results show that the infection of mice with SARS-CoV-2 induces the expression of several pro-inflammatory CC and CXC chemokines activated through NF-kappa B but weakly IL1 beta and IL18 whose expression are more characteristic of inflammasome formation. We also observed the downregulation of several inflammasome effectors. The modulation of innate response, following expressions of non-structural protein 2 (Nsp2) and SARS-CoV-2 infection, was assessed by measuring IFN beta expression and NF-kappa B modulation in human pulmonary cells. A robust activation of the NF-kappa B p65 subunit was induced following the infection of human cells with the corresponding NF-kappa B-driven inflammatory signature. We identified that Nsp2 expression induced the activation of the IFN beta promoter through its NF-kappa B regulatory domain as well as activation of p65 subunit phosphorylation. The present studies suggest that SARS-CoV-2 skews the antiviral response in favor of an NF-kappa B-driven inflammatory response, a hallmark of acute COVID-19 and for which Nsp2 should be considered an important contributor.