[The role of polymorphonuclear cells in lung ischemia-reperfusion injury in a canine model of pulmonary thromboembolism].
OBJECTIVE
To explore the effects of polymorphonuclear cells (PMN) on lung ischemia-reperfusion (I/R) injury in a canine model of pulmonary thromboembolism.


METHODS
Fifteen dogs were divided into three groups: a sham group (n = 5), an ischemia group (n = 5) and a reperfusion group (n = 5). PMN in the whole blood were isolated with density gradient centrifugation. Apoptosis rates of the PMN was measured through flow cytometer after the cells were labeled by Annexin V-FITC before embolectomy and at 2, 4, 6 h after the operation. The myeloperoxidase (MPO) concentrations in lung homogenates were measured by ELISA. Alveolar PMN in the reperfusion lobar were observed by optical microscopy. The lung ultrastructure was studied by transmission electron microscopy.


RESULTS
Alveolar PMN infiltration and the concentrations of MPO in the reperfusion group were significantly higher than those in the ischemia group (PMN (31 +/- 11) vs (8 +/- 4)/ten high power fields, MPO (11.7 +/- 1.6) vs (9.1 +/- 0.5) microg/L, P < 0.05). In the reperfusion group, abundant inflammatory cell infiltration was observed, predominantly with PMN in the alveoli. Apoptosis rates of the blood PMN at 6 h after reperfusion were much lower than before reperfusion (3.0 +/- 2.5)% vs (7.4 +/- 4.5)%, P < 0.05). At 4 and 6 h after operation, the PMN apoptosis rates in the reperfusion group were significantly lower than the ischemia group (4 h: (4.8 +/- 2.6)% vs (9.3 +/- 2.0)%, 6 h: (3.0 +/- 2.5)% vs (8.0 +/- 1.6)%, P < 0.05). PMN attaching firmly to the alveolar septum were observed by electron microscope.


CONCLUSIONS
PMN with enhanced activities and decreased apoptosis rate, are involved in the cellular mechanisms of the lung I/R injury in this model of pulmonary thromboembolism.
Deng
Chao-sheng
CS
Beijing Chaoyang Hospital, Beijing Institute of Respiratory Medicine, Beijing 100020, China.
Wang
Chen
C
Pang
Bao-sen
BS
Yang
Yuan-hua
YH
Du
Min-jie
MJ
Qi
Man
M
Weng
Xin-zhi
XZ
D056809:Alveolar Epithelial Cells; D000818:Animals; D004285:Dogs; D008168:Lung / Q000473:pathology; D009504:Neutrophils / Q000166:cytology*; D011655:Pulmonary Embolism / Q000473:pathology*; D015427:Reperfusion Injury / Q000473:pathology*