Fig. 6: Fluaxe immunization protected lung injury induced by influenza virus infection.

A Images of lungs dissected from mice (Fluaxe and LNP groups) challenged with A/PR/8/1934 (H1N1) on 7 dpi. B H&E staining of PR8-infected lung tissue pathology. Tissue lesions were indicated by narrows as the following: inflammatory cell infiltration predominantly composed of granulocytes (black arrow); congestion of capillaries and venous vessels (yellow arrow); epithelial exfoliation (brown arrow); perivascular edema (purple arrow); loose connective tissue accompanied by mild hemorrhage (green arrow); lymphocyte infiltration (red arrow). Representative images from 5 mice are shown. Scale bar = 100 μm. C Representative images of immunofluorescence staining of (upper panel, green) gap junction protein E-cadherin and (lower panel, green) tight junction protein ZO-1 expressed in lung tissues from 5 mice challenged with PR8. DNA was stained by DAPI in blue. Scale bars = 100 μm. Inflammation-associated cells in lungs were detected on Day 5 post-PR8 infection by FACS. D Frequencies of alveolar macrophages (CD64⁺, CD11c⁺, Siglec F⁺) and interstitial peribronchial macrophages (CD11b⁺, CD11c⁺, CD64⁺, Siglec F⁻, Ly6C⁻) in lungs after mock (PBS) or PR8 infection. Inflammatory macrophages were stained for intracellular NLRP3. E Frequencies classical monocytes (CD11b⁺, Ly6C⁺, CD64⁻) of monocytes-derived cells (CD11b⁺, Ly6C⁺, CD64⁺) and in lungs after mock or PR8 infection. Inflammatory monocytes were stained for intracellular NLRP3. n = 5, data were presented as Mean ± SEM. Statistics were calculated using multiple t-tests with Holm-Šídák’s multiple comparisons. F Influenza virus-induced cytokine expression in the BALFs. BALF cytokine concentrations were determined by a 23-plex assay kit. n = 3. Mean values were shown. p values were calculated by comparing the LNP group and Fluaxe-vaccinated group animals that all were infected with PR8. Significance was calculated using two-tailed unpaired t-tests.