Role of poly (ADP) ribose synthetase in lung ischemia-reperfusion injury.
BACKGROUND
The activation of poly (adenosine diphosphate) ribose synthetase (PARS) is known to be important in the cellular response to oxidative stress. Previous studies have reported that PARS inhibition confers protection in models of endotoxic shock and ischemia-reperfusion. The purpose of this study was to determine the role of PARS inhibition in lung ischemia-reperfusion injury (LIRI).


METHODS
Left lungs of Long-Evans rats were rendered ischemic for 90 minutes and reperfused for up to 4 hours. Treated animals received 3 mg/kg of INO-1001 (a PARS inhibitor) intravenously 30 minutes before ischemia. Injury was quantitated in terms of tissue myeloperoxidase (MPO) content, vascular permeability ((125)I radiolabeled bovine serum albumin extravasation) and bronchoalveolar lavage (BAL) leukocyte content. BAL fluid was assessed for cytokine and chemokine content by enzyme-linked immunoassay. Further samples were processed for nuclear protein analysis by electromobility shift assay (EMSA) and cellular death by terminal deoxyribonucleotidyl transferase-mediated d-UTP biotin nick-end labeling (TUNEL) assay and caspase-3 staining.


RESULTS
Lung vascular permeability was reduced in treated animals by 73% compared with positive controls (p < 0.009). The protective effects of PARS inhibition correlated with a 46% reduction in tissue MPO content (p < 0.008) and marked reductions in BAL leukocyte accumulation. This positively correlated with the diminished expression of pro-inflammatory mediators and nuclear transcription factors, as well as decreased levels of cellular death.


CONCLUSIONS
The deleterious effects of LIRI are in part mediated by the formation of free radicals and superoxides, which lead to DNA single-strand breaks. This leads to activation of PARS, which causes rapid cellular energy depletion and cell death. PARS inhibition is protective against this and represents a potentially useful therapeutic tool in the prevention of LIRI.
Woolley
Steven M
SM
Department of Cardiothoracic Surgery, University of Washington School of Medicine, Seattle, Washington 98195, USA.
Farivar
Alexander S
AS
Naidu
Babu V
BV
Salzman
Andrew
A
Szabo
Csaba
C
Thomas
Robert
R
Fraga
Charles
C
Mulligan
Michael S
MS
D000818:Animals; D007211:Indoles / Q000627:therapeutic use*; D008297:Male; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D015427:Reperfusion Injury / Q000201:enzymology* / Q000517:prevention & control*
C491685:INO 1001; D007211:Indoles; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases