Fig. 4

Inhibitors of endosomal acidification alleviated viral pneumonia in hACE2 transgenic mice. a Images of gross pathology of lungs from hACE2 transgenic mice subjected to indicated treatments. b, c Representative images for H&E staining of histopathological changes in lung tissues from Mock-infected (b) and SARS-CoV-2-challenged hACE2 transgenic mice (c). The numbered panels display magnified images of indicated black circles in the left. SARS-CoV-2 induced histopathological changes as follows: (1) bronchiolar epithelium cell death (yellow arrow) and peribronchiolar infiltration of segmented granulocytes or lymphocytes (black arrow). (2) Inflammatory exudation and infiltration in perivascular tissues (black arrow). (3) Collapse of alveolar structure and widened alveolar septum with inflammatory cell infiltration (black arrow). d, e Representative H&E staining images of lung tissues from SARS-CoV-2-challenged hACE2 transgenic mice that are subjected to chloroquine (d) and bafilomycin A1 (e) treatments. Reduced inflammatory exudation and infiltration in peribronchiolar (1) and perivascular (2) tissues, as well as improved structures of alveolar septum and pulmonary alveoli (3), were observed in chloroquine and bafilomycin A1 treatment groups. Representative images from 6 mice are shown. Black bar = 2 mm. White bar = 200 μm