| Part I The expression of vascular endothelial growth factor in endotoxin-induced acute lung injury modelObjective To investigate the expression of vascular endothelial growth factor in endotoxin-induced acute lung injury model. Methods Thirty male BALB/c mice were randomly assigned to one of the six groups:LPS 4h group, LPS 24h group, LPS 48h group, PBS 4h group, PBS 24h group, and PBS 48h group. All animals were anesthetized by pentobarbital sodium. LPS (3 mg/kg) was intratracheally instilled via tracheal tube through the trachea to the mice in the LPS group. Mice in the PBS group were instilled an equal volume of PBS as control. Blood gas analysis and vascular endothelial growth factor (VEGF) were measured at predefined time points. Pathohistological change, VEGF and total protein levels in bronchoalveolar lavage fluid were measured. Result Endotoxin administration resulted in an elevation of VEGF (12.44±4.05 pg/ml vs 31.53±1.96 pg/ml, P<0.05) associated with hypoxia (97.27±8.96 mmHg vs 64.24±10.53 mmHg, P< 0.001), carbon dioxide accumulation (37.83±5.75 mmHg vs 49.00±9.19 mmHg, P< 0.05), pulmonary edema, an increase of total protein (183.28±15.58μg/ml vs 569.17±114.68μg/ml, P< 0.05) and VEGF (32.45±6.57 pg/ml vs 160.14±34.25 pg/ml, P< 0.05) in bronchoalveolar lavage fluid. Total protein significantly correlated with VEGF in bronchoalveolar lavage fluid (r=0.676, P< 0.001). The extent of histological abnormalities as assessed by lung injury score peaked at 24 h after LPS challenge.Conclusion Our research indicated that increased VEGF expression may be implicated in the pathogenesis of endotoxin-induced acute lung injury model. Part II Protective effects of anti-vascular endothelial growth factor therapy in endotoxin-induced acute lung injury modelObjective To explore the effect of intervention with anti-vascular endothelial growth factor in endotoxin-induced acute lung injury (ALI) model. Methods Sixty mice were randomly assigned to the PBS group (n=15), LPS group (n=15), sFlt group (n=15), and LPS+sFlt group (n=15). Mice in the four groups were then subdivided into three subgroups (4 h,24 h, and 48 h groups, n=5), respectively. All animals were anesthetized by pentobarbital sodium. LPS (3 mg/kg) was intratracheally instilled via tracheal tube through the trachea to the mice in the LPS group and LPS+sFlt group. Mice in the PBS group and sFlt group were instilled an equal volume of PBS as control. Then sFlt-1(50μg/kg) was infused via tail vein to the mice in the sFlt and LPS+sFlt group. The mice in the PBS and LPS groups were given an equal volume of PBS as control. At predefined time points blood gas analysis, pathohistological change, VEGF and total protein levels in bronchoalveolar lavage fluid were measured. Result Anti-VEGF therapy with sFlt-1 attenuated the hypoxia (64.24±10.53 mmHg vs 84.31±7.23 mmHg, P<0.001), carbon dioxide accumulation (49.00±9.19 mmHg vs 36.51±4.83 mmHg, P< 0.05), and total protein (569.17±114.68μg/ml vs 264.82±76.92μg/ml, P< 0.05) in bronchoalveolar lavage fluid. sFlt-1 administration did not change the level of VEGF in plasma (31.53±1.96 pg/ml vs 39.69±8.98 pg/ml, P>0.05) and BALF (160.14±34.25 pg/ml vs 127.52±17.83 pg/ml, P>0.05). Conclusion Anti-VEGF therapy with sFlt-1 improves the blood gas analysis and attenuates pathohistological development of ALI. sFlt-1 administration might attenuate the thickness of the alveolar-capillary membrane. Part III Protective effects and mechanisms of anti-vascular endothelialgrowth factor therapy in endotoxin-induced acute lung injury modelObjective To investigate the possible mechanism of anti-VEGF therapy in endotoxin-induced acute lung injury (ALI) model. Methods Sixty mice were randomly assigned to the PBS group (n=15), LPS group (n=15), sFlt group (n=15), and LPS+sFlt group (n=15). Mice in the four groups were then subdivided into three subgroups (4 h,24 h, and 48 h groups, n=5), respectively. All animals were anesthetized by pentobarbital sodium. LPS (3 mg/kg) was intratracheally instilled via tracheal tube through the trachea to the mice in the LPS group and LPS+sFlt group. Mice in the PBS group and sFlt group were instilled an equal volume of PBS.Then sFlt-1 (50μg/kg) was infused via tail vein to the mice in the sFlt and LPS+sFlt group. The mice in the PBS and LPS groups were given an equal volume of PBS. At predefined time points, pathohistology of alveolar epithelial barrier, apoptosis index, and the anti-apoptotic protein mRNA express were studied. Result PBS and sFlt group showed intact alveolar-capillary membrane, whereas LPS challenge caused the solution of tight junction between alveolar epithelial cells, type I alveolar epithelial cell shrinkage and detachment from the basement membrane, thickness of the alveolar-capillary membrane and infiltration of cellulose into alveolar spaces. sFlt-1 administration attenuated the solution of tight junction and the thickness of the alveolar-capillary membrane in LPS+sFlt group, but sFlt-1 did not increased the alveoli epithelial cells apoptosis index. Conclusion VEGF causes an increase in the permeability of the lung by breaking lung alveolar-capillary barrier. Anti-VEGF therapy improves the blood gas analysis and attenuates pathohistological development of ALI by decreasing the permeability of alveolar epithelial barrier. Conclusion1. LPS-induced ALI is associated with increased mRNA expression of VEGF in lung tissue and elevated levels of VEGF in blood, lung, and BALF.2. Increased VEGF causes an increase in the permeability of the lung by breaking lung alveolar-capillary barrier.3. Anti-VEGF therapy improves the blood gas analysis and attenuates pathohistological development of ALI.4. Reducing VEGF by treatment with sFlt-1 attenuates the pulmonary edema by decreasing decreasing the permeability of alveolar epithelial barrier. |
