Fig 2: The histological changes from the mouse lung tissues with injection of PU.1/CD23-ERFP-expressing adenovirus (Ad-PU.1 and Ad-CD23 respectively). A-C ERFP signals detected in Ad-PU.1 and Ad-CD23 mouse lung tissues. D Relative levels of PU.1 and CD23 quantified by ERFP fluorescence. Adenovirus expression ERFP served as a control. E HE staining from mouse lung tissues injected with Ad-PU.1 and Ad-CD23 adenovirus in AF infection. Normal saline (NS) conditions and empty vector served as controls. All data are presented as the mean ± SD, N = 3, **P < 0.01. Bars = 200 µm

Fig 3: A schematic depicting the PU.1-CD23 axis regulating inflammation response under AF conditions

Fig 4: The expressions of PU.1, CD23, p-ERK, CCL20 and IL-8 in Ad-PU.1/Ad-CD23 mouse lung tissues under AF infecton and NS treatment. A Immunochemistry results showed the protein expressions of PU.1 and CD23 in mouse lung tissues injected with Ad-PU.1 and Ad-CD23 adenovirus with AF infection compared to the NS conditions. B, C The quantitative analysis of PU.1 and CD23 expressions in A. NS conditions and empty vector served as controls. D The western blotting analysis showed the protein levels of PU.1, CD23, p-ERK, CCL20 and IL-8 in mouse lung tissues injected with Ad-PU.1 adenovirus with AF infection compared to the NS treatment. The samples derived from the same experiment and that gels/blots were processed in parallel. E–I The quantification of protein levels in D. All data are presented as the mean ± SD, N = 3, *P < 0.05, **P < 0.01. Bars = 200 µm

Fig 5: PU.1 directly activated the expression of CD23 in HTMs with AF infection. A Luciferase reporter plasmid containing two putative PU.1 binding sites in the CD23 promoter (2500 bp upstream of the ATG) compared to the full-length promoter deletion (300 bp upstream of the ATG). B Dual luciferase reporter assay showed that PU.1 could activate the LUC signal in the construct containing sequences from 2500 bp upstream of the ATG to 50 bp downstream of ATP. The luciferase activities were normalized to the ß-galactosidase levels of the control. C Three artificial mutations in the PU.1 binding sites of the CD23 promoter. D Relative LUC activity showed the activating efficiency of PU.1 to the three artificial mutated CD23 promoters. E CD23 promoter revealed two putative PU.1 binding sites starting at -695 and -326. F Relative DNA levels of the CD23 promoter region containing two PU.1 binding sites from ChIP assay were detected by qPCR. G Percentage relative to input DNA for PU.1 ChIP was quantified. H EMSA showed that the PU.1 protein could bind to the CD23 promoter region in vitro. All data are presented as the mean ± SD, N = 3, *P < 0.05, **P < 0.01