Figure 5. Airway epithelial cell proteome changes after elastase (PPE) administration.

(A) H&E-stained section of bronchi before (left) and after epithelial cell isolation (right). Scale bars: (left) 200 μm, (right) 50 μm. (B) Heatmap of the most changed proteins in the airway epithelial cell proteome after PPE exposure. (C and D) The most abundant proteins in airway epithelial cells detected by label-free proteomics after saline (C) and PPE (D) instillation. (E) Label-free quantification (LFQ) of the most changed proteins after PPE exposure, n = 7 pools/group with 3 mice/pool, data presented as median ± IQR, *P = 0.017, **P = 0.006, ***P = 0.0006, Mann-Whitney U test. The detection limit for Muc5ac was set to 1 × 10⁶. (F) Absolute quantification of Muc5ac and Muc5b with isotopically labeled peptides by mass spectrometry; n = 8 pools/group with 3 mice/pool, data presented as median ± IQR, **P = 0.001, Mann-Whitney U test. Detection limit for Muc5ac was set to 1 fmol. (G) Ratio of Muc5ac to Muc5b in isolated mucus plugs, BALF supernatants (BALF SN), and epithelial cells, n = 6–12 samples/group. Data presented as median ± IQR, *P = 0.04, **P = 0.0016, Kruskal-Wallis and Dunn’s multiple comparisons test. Chi3l4, chitinase-3-like protein 4; Clca1, chloride channel accessory 1; Retnla, resistin-like α; Chi3l3, chitinase-3-like protein 3; Ltf, lactotransferrin; C3, complement C3; Agr2, anterior gradient protein 2 homolog; Cp, ceruloplasmin; Bpifb1, BPI fold-containing family B member 1; Chi3l1, chitinase-3-like protein 1; Scin, adseverin; Fcgbp, Fcgbp protein; Pla2g4c, Pla2g4c protein; St3gal4, β-galactoside α-2,3-sialyltransferase 4; Tff2, trefoil factor 2; Pglyrp1, peptidoglycan recognition protein 1; Reg3g, regenerating islet-derived protein 3-γ; Qsox1, sulfhydryl oxidase 1; Chia, acidic mammalian chitinase; Chad, chondroadherin; Fer1l6, Fer-1-like 6; Fn1, fibronectin; Cbr2, carbonyl reductase [NADPH] 2; Aldh1a1, retinal dehydrogenase 1; Sec14l3, SEC14-like 3; Hist1h2bj, histone H2B; Scgb1a1, uteroglobin.