Fig. 5: Pretreatment with recombinant TRAIL attenuates hyperoxia-induced lung injury in PCLS from wildtype and TRAIL^−/− mice.

A Haematoxylin/eosin staining of precision cut lung slices (PCLS) of newborn mice pretreated with recombinant TRAIL (100 ng/ml) at P2 before exposure to 21% or 80% of oxygen for 3 days. PCLS were re-stimulated with TRAIL every 24 h. PCLS displayed the characteristic morphologic features of hyperoxic injury after 72 h similar to the in vivo situation presented in Fig. 2A–C that was inhibited by pretreatment with TRAIL. Scale bar: 200 µm. B Corresponding lung morphometric analyses for airspace (left panel), mean septal wall thickness (right panel) and linear intercept (lower panel) of PCLS from A. Hyperoxia-induced increase in airspace and mean linear intercept was present to an equal extent in PCLS from wildtype and TRAIL^−/− mice. TRAIL pretreatment rescued lung development both in wildtype and TRAIL^−/− animals. C Immunofluorescence staining for SPC positive alveolar type II cells in PCLS from A. PCLS from wildtype and TRAIL^−/− animals exhibited rarefication of SPC positive cells after hyperoxic injury that was inhibited by pretreatment with TRAIL. D Quantification of SPC positive cells from C. Hyperoxia-induced rarefication of SPC positive cells was similar in PCLS from wildtype and TRAIL^−/− mice. TRAIL pretreatment rescued the presence of SPC positive cells both in wildtype and TRAIL^−/− animals. E Immunofluorescence staining for CD31 positive vascular endothelial cells in PCLS from A. PCLS from wildtype and TRAIL^−/− animals demonstrated rarefication of CD31 positive cells after hyperoxic injury that was inhibited by pretreatment with TRAIL. F Quantification of CD31 positive cells from E. Hyperoxia-induced rarefication of CD31 positive cells was similarly pronounced in PCLS from wildtype and TRAIL^−/− mice. TRAIL pretreatment rescued the presence of CD31 positive cells both in wildtype and TRAIL^−/− animals. G Immunofluorescence staining for PDGFRα positive mesenchymal progenitor cells in PCLS from A. PCLS from wildtype and TRAIL^−/− animals displayed rarefication of PDGFRα positive cells after hyperoxic injury that was inhibited by pretreatment with TRAIL. H Quantification of PDGFRα positive cells from G. Hyperoxia-induced rarefication of PDGFRα positive cells was similarly pronounced in PCLS from wildtype and TRAIL^−/− mice. TRAIL pretreatment rescued the presence of PDGFRα positive cells both in wildtype and TRAIL^−/− animals. Data are presented as mean + SEM. Statistical analysis was performed by t-test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. n ≥ 3 mice/group.