Figure 3

The emphysematous lung is abnormally sensitive to TRAIL-mediated apoptosis ex vivo. [A] Caspase-3 activity and active caspase-8 levels were assessed at 0, 6, 12 and 18 h in untreated and rTRAIL-treated lung explants from non-emphysematous (grey) and emphysematous subjects (black). For every subject, values obtained were used to determine the area under the curve (AUC) for untreated and rTRAIL-treated explants. The percentage of variation of the AUC was then determined for every subject ([AUC rTRAIL-treated/AUC untreated]*100). A positive percentage means that rTRAIL induced caspases activation. [B] TUNEL staining was performed on explants from every subject after 18 h of TRAIL treatment or culture control. Every TUNEL⁺ (apoptotic) and DAPI⁺ (nucleus) cells were counted and then the percentage of TUNEL⁺ was determined for every condition ([TUNEL⁺/DAPI⁺]*100). For every subject, the effect of 18 h treatment of TRAIL on apoptosis induction was then determined as follow: %TUNEL⁺ TRAIL-treated - %TUNEL⁺ untreated. [C] Representative TUNEL staining of a lung explant used to measure TRAIL-induced apoptosis ex vivo. Results are expressed as means ± SEM. *p < 0.05, **p < 0.01.