The nuclear
enzyme poly(ADP-ribose)polymerase (PARP) plays a significant role in the pathogenesis of various forms of
critical illness.
DNA strand breaks induced by oxidative and nitrative stress trigger the activation of PARP, and PARP, in turn, mediates cell death and promotes proinflammatory responses. Until recently, most studies focused on the role of PARP in solid organs such as heart, liver, and kidney. We investigated the effect of
burn and
smoke inhalation on the levels of
poly(ADP-ribosylated) proteins in circulating sheep leukocytes ex vivo. Adult female merino sheep were subjected to
burn injury (2× 20% each flank, 3 degrees) and
smoke inhalation injury (insufflated with a total of 48 breaths of cotton
smoke) under deep
anesthesia. Arterial and venous blood was collected at baseline, immediately after the injury and 1 to 24 h after the injury. Leukocytes were isolated with the
Histopaque method. The levels of poly(
ADP-ribosyl)ated
proteins were determined by Western blotting. The amount of
reactive oxygen species was quantified by the OxyBlot method. To examine whether PARP activation continues to increase ex vivo in the leukocytes, blood samples were incubated at room temperature or at 37°C for 3 h with or without the
PARP inhibitor PJ34. To investigate whether the plasma of
burn/
smoke animals may trigger PARP activation,
burn/
smoke plasma was incubated with control leukocytes in vitro. The results show that
burn and
smoke injury induced a marked PARP activation in circulating leukocytes. The activity was the highest immediately after injury and at 1 h and decreased gradually over time. Incubation of whole blood at 37°C for 3 h significantly increased
poly(ADP-ribose) levels, indicative of the presence of an ongoing cell activation process. In conclusion, PARP activity is elevated in leukocytes after
burn and
smoke inhalation injury, and the response parallels the time course of
reactive oxygen species generation in these cells.