Fig. 1

Newly detected Siglec-F⁺ neutrophils in the lungs of PPE-induced emphysema mice. A Representative FACS plot showing the CD11b⁺ cell gate and the frequency of Siglec-F⁺ neutrophils in the lungs of PPE-instilled mice on day 4 (n = 5 per group). B Frequencies of Siglec-F⁺ neutrophils assessed daily over 7 days in the lungs of PPE-instilled mice (n = 4 per group). C Frequencies of Siglec-F⁺ neutrophils in the organs of PPE-instilled mice on day 4 (n = 4 per group). D Representative FACS plots showing the CD11b⁺ cell gate in the lungs of PPE-induced emphysema mice assessed 5 min after intravenous staining with anti-CD45-PE. The frequencies of PE⁺ circulating, PE^-- resident conventional, and Siglec-F⁺ neutrophils were assessed (n = 4 per group). E Neutrophils harvested from the lungs of PPE-induced emphysema mice on day 4 were cultured with AF647-labeled OVA for 3 h. AF647⁺ cells were then analyzed to assess phagocytic activity (n = 4 per group). F Neutrophils were isolated from the lungs of PPE-induced emphysema mice on day 4 and then treated with 5 μM PMA for 4 h. NET formation in conventional neutrophils and Siglec-F⁺ neutrophils was assessed by staining with SYTOX Green (n = 4 per group). G The levels of cytokines secreted by conventional neutrophils and Siglec-F⁺ neutrophils sorted from the lungs of PPE-induced emphysema mice on day 4 were measured 24 h after stimulation with LPS (n = 4 per group). H Conventional neutrophils and Siglec-F⁺ neutrophils sorted from the lungs of PPE-induced emphysema mice on day 4 were intratracheally transferred into WT mice. Lung tissue histology after H&E staining and the mean linear intercept (MLI) of the recipient mice were then assessed. Scale bar = 200 μm (n = 5 per group). Unpaired two-tailed Student’s t test with Welch’s correction A, C, G, unpaired one-way ANOVA with Dunnett’s T3 post hoc test B, H, and unpaired two-way ANOVA with Tukey’s post hoc test D–F were used to measure significance. *P < 0.05, **P < 0.01, ***P < 0.001; ns, not significant; error bars indicate the means ± SDs