ABSTRACT
@#Abstract: Objective To explore the antiviral effect of baricitinib in the SARS-CoV-2 infection and influence on cytokine levels. Methods Calu-3 cells were infected with SARS-CoV-2 at MOI of 0.1, and the levels of inflammatory cytokines (IL-6, IL-8, TNF-α and IL-1β), interferon β (IFN-β) and interferon-stimulated gene, IFIT2 in the infected cells were analyzed by qRT-PCR methods. At the same time, Calu-3 cells were infected with SARS-CoV-2 (MOI=0.1) after being treated with baricitinib for 2 hours. Cells were collected at 0, 24, 36, and 48 hours, and analyzed for the mRNA of the above genes in the drug-treated and untreated groups. Results The mRNA levels of IL-6, TNF-a, IL-1β, IFN-β and IFIT2 in Calu-3 infected by SARS-CoV-2 cells were increased significantly. These cytokines were increased by nearly 100-fold post-infection 48 h compared with the control (P<0.000 1), and continued to increase with the infection time (P<0.001 or P<0.000 1). The increase of IL-8 mRNA level was not as significant as IL-6, TNF-α, IL-8, IL-1β, but it also showed a 2-4 folds increase. Baricitinib does not affect the level of viral RNA in Calu-3 cells after SARS-CoV-2 infection (P>0.05). However, baricitinib can significantly inhibit the up-regulation of IL-6 and TNF-α levels induced by SARS-CoV-2 infection (5.25-fold and 3.90-fold down-regulation, respectively, P<0.01), and has little effect on the levels of IL-8 and IL-1β . In addition, the drug could also significantly down-regulate the increase in IFN-β and IFIT2 levels caused by viral infection (10.51-fold and 90.78-fold down-regulation, respectively, P<0.000 1). Conclusions Baricitinib inhibits the release of inflammatory cytokines to some extent, but it drastically down-regulates the expression of interferons and interferon-stimulated genes (ISGs), and has limited antiviral effect on SARS-CoV-2. Considering that interferon signal pathways play important roles on viral infection, caution should be exercised when using baricitinib to treat COVID-19 patients.