Enhanced fibrinolysis protects against lung ischemia-reperfusion injury.
OBJECTIVE
Ischemia-reperfusion injury continues to plague the field of lung transplantation, resulting in suboptimal outcomes. In acute lung injury, processes such as ventilator-induced injury, sepsis, or acute respiratory distress syndrome, extravascular fibrin has been shown to promote lung dysfunction and the acute inflammatory response. This study investigates the role of the fibrinolytic cascade in lung ischemia-reperfusion injury and investigates the interplay between the fibrinolytic system and the inflammatory response.


METHODS
Mice lacking the plasminogen activator inhibitor-1 gene (PAI-1 knock out, PAI-1 KO; and thus increased lysis of endogenous fibrin) and wild-type mice underwent in situ left lung ischemia and reperfusion. Fibrin content in the lung was evaluated by immunoblotting. Reperfusion injury was assessed by histologic and physiologic parameters. Proinflammatory mediators were measured in bronchoalveolar lavage fluid and plasma using enzyme-linked immunosorbent assays.


RESULTS
Ischemia-reperfusion causes fibrin deposition in murine lungs. Less fibrin was seen in PAI-1 KO mice than in wild-type mice subjected to the same ischemia-reperfusion conditions. By histologic criteria, more evidence of ischemia-reperfusion injury was noted (thickening of the interstium, cellular infiltration in the alveoli) in the wild-type than in PAI-1 KO mice. Physiologic parameters also revealed more ischemia-reperfusion injury in the wild-type than in PAI-1 KO mice. Cytokine and chemokines were elevated more in the wild-type group than the PAI-1 KO group.


CONCLUSIONS
Lung ischemia-reperfusion injury triggers fibrin deposition in the murine lungs and fibrin creates a proinflammatory environment. Preventing fibrin deposition may reduce ischemia-reperfusion injury and inflammation. This finding may lead to novel treatment strategies for ischemia-reperfusion.
Lau
Christine L
CL
Division of Thoracic and Cardiovascular Surgery, University of Virginia, Charlottesville, Va., USA.
Zhao
Yunge
Y
Kim
Jiyoun
J
Kron
Irving L
IL
Sharma
Ashish
A
Yang
Zequan
Z
Laubach
Victor E
VE
Linden
Joel
J
Ailawadi
Gorav
G
Pinsky
David J
DJ
D055371:Acute Lung Injury / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005337:Fibrin / Q000378:metabolism*; D005342:Fibrinolysis; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000378:metabolism; D007511:Ischemia / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism*; D011336:Probability; D011897:Random Allocation; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D012680:Sensitivity and Specificity
D018925:Chemokines; D016207:Cytokines; D018836:Inflammation Mediators; D017395:Plasminogen Activator Inhibitor 1; D005337:Fibrin