Protection by 20-5,14-HEDGE against surgically induced ischemia reperfusion lung injury in rats

  • Ann Thorac Surg. 2012 Jan;93(1):282-8. doi: 10.1016/j.athoracsur.2011.08.074.
Irshad Ali  1 ,  Stephanie Gruenloh ,  Ying Gao ,  Anne Clough ,  John R Falck ,  Meetha Medhora ,  Elizabeth R Jacobs
Affiliations
  • 1. Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
PMID: 22115333 DOI: 10.1016/j.athoracsur.2011.08.074
Abstract

Background: We previously reported that the Cytochrome P450 product 20-hydroxyeicosatetraenoic acid has prosurvival effects in pulmonary artery endothelial cells and ex vivo pulmonary arteries. We tested the potential of a 20-hydroxyeicosatetraenoic acid analog N-[20-hydroxyeicosa-5(Z),14(Z)-dienoyl]glycine (20-5,14-HEDGE) to protect against lung ischemic reperfusion injury in rats. Furthermore, we examined activation of innate immune system components, high mobility group box 1 (HMGB1) and Toll-like Receptor 4 (TLR4), in this model as well as the effect of 20-5,14-HEDGE on this signaling pathway.

Methods: Sprague-Dawley rats treated with 20-5,14-HEDGE or vehicle were subjected to surgically induced, unilateral lung ischemia for 60 minutes followed by reperfusion for 2 hours in vivo. Injury was assessed histologically by hematoxylin and eosin, and with identification of myeloperoxidase immunohistochemically. The HMGB1 and TLR4 proteins were identified by Western blot. Caspase 3 activity or 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole, incorporation were used to measure Apoptosis and cell survival.

Results: The ischemia reperfusion injury evoked atelectasis and hemorrhage, an influx of polymorphonuclear cells, and increased TLR4 and HMGB1 expression. Caspase 3 activity was increased, and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide incorporation was decreased. The 20-5,14-HEDGE protected against each of these endpoints, including infiltration of polymorphonuclear cells, with no changes in Caspase 3 activity in Other organs.

Conclusions: Lung ischemia reperfusion produces Apoptosis and activation of the innate immune system including HMGB1 and TLR4 within 2 hours of reperfusion. Treatment with 20-5,14-HEDGE decreases activation of this response system, and salvages lung tissue.

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