Fig. 4. Pan-MMP inhibitors reduce WT SARS-CoV-2 replication in vitro and in vivo.

(A and B) Calu3 and Caco2 cells were treated with DMSO, pan-serine protease inhibitor (camostat), pan-MMP inhibitors (prinomastat, incyclinide, and 20(R)-ginsenoside Rh2) or at the indicated combination for 2 hours at 37°C. The pretreated cells were challenged with SARS-CoV-2 WT. Supernatant samples were harvested at 24 hpi for qRT-PCR analysis (n = 4). (C) Schematic the pan-MMP inhibitor experiment in golden hamsters. (D and E) Golden hamster lung samples were harvested on day 2 after SARS-CoV-2 WT challenge and homogenized for qRT-PCR analysis and plaque assay titration (n = 4). (F) Representative immunofluorescence images of infected hamster lungs with or without treatments. SARS-CoV-2 nucleocapsid (N) protein was identified with a rabbit anti–SARS-CoV-2-N immune serum (green), and nuclei was identified with 4′,6-diamidino-2-phenylindole (DAPI) stain (blue). (G) Representative hematoxylin and eosin images of infected hamster lungs with or without treatments. Representative regions of (i) bronchiole epithelium and (ii) alveolar space were shown. Scale bars in (F) and (G) represented 500 or 200 μm for 4-fold or 10-fold magnifications of the objective, respectively, with ×10 magnification at the eyepiece. The experiments in (A) and (B) and (D) to (G) were repeated three times and two times independently with similar results, respectively. Data represented means and SDs from the indicated number of biological repeats. Statistical significance between groups in (A) and (B), and (D) and (E) was determined with two-way and one-way ANOVA, respectively. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001.