| Objective:To investigate the expression of prostacyclin in lungs from patients with chronic obstructive pulmonary disease and the protective effect of prostacyclin on the endothelial cell apoptosis induced by cigarette smoking extract.Methods:1.The lung tissues were obtained from 12 patients with COPD and 10 patients without COPD.Pathological changes of lung tissue were assessed through HE staining.The apoptotic statement of pulmonary vascular endothelial cells was analyzed quantitatively using TdT-mediated dUTP nick end labeling(TUNEL).The expression of PGI2-S protein was assessed by immunohistochemistry of paraffin-embedded tissues.6-keto Prostaglandin F1a,the stable metabolite of PGI2,was measured by enzyme-linked immunosorbent assay in whole-lung tissue extracts.2.Human umbilical vascular endothelial cells (HUVEC)were cultured in vitro:①HUVEC were interfered with 0%, 0.5%,1%,2.5%,5%and 10%CSE for 24h.Caspase-3 activity was tested by absorption spectrometry.The expression of PGI2-S protein was assessed by immunohistochemistry.And 6-keto Prostaglandin F1a,the stable metabolite of PGI2,was measured by enzyme-linked immunosorbent assay in cells culture fluid.②HUVEC were exposed to 2.5%CSE for 3h,6h,9h,12h,24h and 48h respectively,and then 6-keto Prostaglandin Fla was measured by enzyme-linked immunosorbent assay in cells culture fluid③HUVEC were treated with 2.5%CSE and different concentrations of prostacyclin analogues-beraprost sodium(10-8mmol/L, 10-7mmol/L,10-6 mmol/L,10-5 mmol/L) together for 24h.Caspase 3 activity was tested by absorption spectrometry and the apoptotic statement of cells was analyzed quantitatively using TdT-mediated dUTP nick end labeling(TUNEL).Results:1.①The apoptotic index(AI) of endothelial cells of medium and small-sized vessels in patients with COPD group [(12.9±2.0)%,(11.4±1.4)%]were significantly higher than that of patients without COPD groups[(6.1±1.2)%,(5.9±0.4)%].In patients without COPD group,PGI2-S protein expression in medium vessels and small-sized vessels was(95.4±2.1)%and(82.3±7.4)%respectively,and the value was(95.5±2.2)%in airway epithelial cells.In patients with COPD group,PGI2-S expression in medium vessels and small-sized vessels decreased remarkably[(55.2±9.8)%and(42.3±5.1)% respectively],and exhibited a more obvious reduction in airway epithelial cells(31.8±5.2)%.6-keto Prostaglandin Fla levels decreased significantly in patients with COPD(2.6±0.4) ng/ml compared with patients without-COPD(16.2±2.8) ng/ml.2.①At lower concentrations of CSE(≤2.5%),with the increasing of the CSE concentration,the activity of caspase-3 showed an increasing tendency,[(226.54±6.56)%, (235.06±16.25)%and(253.94±20.74)%respectively],but the increasing differences have no statistical significance.At higher concentrations of CSE(＞2.5%),however,the activity of caspase-3 decreased dramatically,and presented significant differences when compared with its activity treated with 2.5%CSE.In addition,the expression of prostacyclin synthease and the releasing of 6-keto Prostaglandin F1a decreased gradually with the increasing CSE concentration.②After treated with 2.5%CSE for 3h,the cellular secretion of 6-keto Prostaglandin F1a began to decline,and reached its lowest peak at 9h.Then it rose with a small extent,and showed a significant rising after 48h treatment.③Prostacyclin analogues-beraprost sodium can effectively decreased the activity of caspase-3 induced by CSE and percentage of apoptotic endothelial cells,but with a insignificant dose-effect relationship.Conclusions:1.①Abnormal apoptosis exists in pulmonary vascular endothelial cells in patients with COPD.②In patients with COPD,The expression of PGI2-S in lung tissue decreases,with a most remarkable reduction in airway epithelial cells and a less remarkable reduction in endothelial cells of medium.③In patients with COPD,the generation of PGI2 in lung tissue decreased significantly.2.Cigarette smoking extract may contribute to endothelial cell apoptosis,and prostacyclin can partly prevent the endothelial cell apoptosis induced by CSE.
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