Figure 1.
Platelets are required for the clearance of intra-alveolar neutrophils. Bacterial pneumonia was induced in WT, PF4+/+iDTR+DT, PF4−/−iDTR+DT, Mrp8+/+iDTR+DT, Mrp8−/−iDTR+DT, and Mrp8−/−iDTR-DT mice by i.t. instillation of viable K. pneumoniae (1.5 × 107 CFU/mouse). WT mice received a platelet-depleting antibody (clone R300, 2 µg/g body weight) or isotype control IgG 2 d after induction of pneumonia. All conditional iDTR mice were treated with DT (+DT) on day 2. (A and B) The number of neutrophils in the BAL fluid (A) and the percentage of apoptotic neutrophils in the BAL (B) was analyzed by flow cytometry (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05). Arrows indicate time point of platelet depletion. (C and D) Likewise, the number of neutrophils in the interstitial space (IS; C) and the percentage of apoptotic neutrophils in the interstitial space (D) was analyzed (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05). (E and F) 14 d after induction of pneumonia, lung collagen content (estimated by measuring the absorbance of oxidized hydroxyproline in lung tissue homogenisates; E) and lung compliance (F) were analyzed in PF4−/−iDTR+DT mice and in PF4+/+iDTR+DT mice with or without DRB, Mrp8+/+iDTR+DT, Mrp8−/−iDTR+DT, and Mrp8−/−iDTR-DT (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05). (G) Exemplary histological images of Masson-Goldner staining of DRB-treated PF4−/−iDTR+DT and PF4+/+iDTR+DT as well as Mrp8+/+iDTR+DT mice to visualize collagen fiber (blue) deposition. Scale bar, 100 µm. (H) Histological lung fibrosis was quantified using the Ashcroft scoring system (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05).

Platelets are required for the clearance of intra-alveolar neutrophils. Bacterial pneumonia was induced in WT, PF4+/+iDTR+DT, PF4−/−iDTR+DT, Mrp8+/+iDTR+DT, Mrp8−/−iDTR+DT, and Mrp8−/−iDTR-DT mice by i.t. instillation of viable K. pneumoniae (1.5 × 107 CFU/mouse). WT mice received a platelet-depleting antibody (clone R300, 2 µg/g body weight) or isotype control IgG 2 d after induction of pneumonia. All conditional iDTR mice were treated with DT (+DT) on day 2. (A and B) The number of neutrophils in the BAL fluid (A) and the percentage of apoptotic neutrophils in the BAL (B) was analyzed by flow cytometry (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05). Arrows indicate time point of platelet depletion. (C and D) Likewise, the number of neutrophils in the interstitial space (IS; C) and the percentage of apoptotic neutrophils in the interstitial space (D) was analyzed (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05). (E and F) 14 d after induction of pneumonia, lung collagen content (estimated by measuring the absorbance of oxidized hydroxyproline in lung tissue homogenisates; E) and lung compliance (F) were analyzed in PF4−/−iDTR+DT mice and in PF4+/+iDTR+DT mice with or without DRB, Mrp8+/+iDTR+DT, Mrp8−/−iDTR+DT, and Mrp8−/−iDTR-DT (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05). (G) Exemplary histological images of Masson-Goldner staining of DRB-treated PF4−/−iDTR+DT and PF4+/+iDTR+DT as well as Mrp8+/+iDTR+DT mice to visualize collagen fiber (blue) deposition. Scale bar, 100 µm. (H) Histological lung fibrosis was quantified using the Ashcroft scoring system (data pooled from at least two independent experiments with four to six mice in each group; Mann-Whitney test was used for statistical analysis, *, P < 0.05).

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