Figure 6. Neutrophil depletion prevents disruption of elastic fibers in saccular-stage IKTA lungs.

Control and IKTA pups were administered anti-ly6G antibodies or control IgG IP on P2 prior to placing dams on Dox from P3 to P5 for transgene activation. (A) Expression of Eln and Fbln5 in P5 lungs. Data are expressed as mean ± SEM, n = 6 per group, *P < 0.05 by 1-way ANOVA and post hoc Tukey test. (B) Representative photomicrographs of RNAscope-labeled sections from P5 lungs. Fbln5- and Eln-expressing cells were reduced in IKTA lungs with control IgG treatment, but Fbln5 and Eln expression appeared similar to controls in IKTA mice with anti-Ly6G antibody treatment. (C) Representative Hart’s elastin–stained sections from P5 lungs showing normal cord-like structures around airspaces in IKTA mice treated with anti-Ly6G antibodies. Arrows denote elastic fibers around airspaces. Arrowhead denotes fragmented elastic fibers. (D and E) CD11b⁺ Ly6G⁺ neutrophils were isolated from IKTA lungs and cocultured with wild-type saccular-stage lung fibroblast for 4 hours. Expression of Fbln5 (D) and Eln (E) was reduced in saccular-stage lung fibroblasts cocultured with IKTA neutrophils. Data are expressed as mean ± SEM, n = 3 per group. Data are representative of 3 independent experiments. (D and E), *P < 0.05 by 2-tailed Student’s t test. Scale bar: 10 μm in B, 50 μm in C.