Fig. 5

FNC-protected thymus from the damage by SARS-CoV-2 infection. By the end of the experiment, the RM monkeys have practiced euthanasia, and the thymus samples were collected. a The representative images of the multi-color immunofluorescent staining were for ACE2 (red) and S protein (green) in the thymus of the RM monkeys that were inoculated with SARS-CoV-2 and treated or untreated with FNC. The regions of interest (ROI) are boxed in white, and their magnified photos are shown in the middle, with a decomposition diagram on the right. Scale bars, 200 µm (left) and 20 µm (middle and right). b Representative images of tissue flow cytometry analysis, using Tissue FAXS platform and Tissue Quest software (Tissue Gnostics), showed that S-protein positive cells were decreased by FNC. c Statistical results of ACE2 and S-protein positive cells in the thymus of the FNC-treated group and the untreated one (n = 4 for each group) showed that FNC significantly reduced the cells infected with SARS-CoV-2. d FNC alleviated infiltration, effusion, and structure damage (white arrows) in the thymus of the FNC-treated virus (+) monkeys. The regions of interest (ROI) are boxed in white, and their magnified photos are shown below. Data are presented as mean ± SEM (n = 4), *p < 0.05, FNC-treated group vs. untreated group, by Mann–Whitney U test