Role of interleukin 18 in acute lung inflammation induced by gut ischemia repeifusion

AIM: To study the changes of endogenous interleukin 18 (IL-18) levels and evaluate the role of IL-18 on lung injury following gut ischemia/reperfusion.METHODS: A superior mesenteric artery occlusion model was selected for this research. The mice were randomly divided into four groups: Sham operation (sham), ischemia (0.5 h) followed by different times of reperfusion (I/R),and I/R pretreated with exogenous IL-18 (I/R+IL-18) or IL-18 neutralizing antibody (I/R+IL-18Ab) 15 min before ischemia. Serum IL-18 levels were detected by Western blot and ELISA, and the levels of IL-18 in lung tissue were evaluated by immunohistochemical staining. For the study of pulmonary inflammation, the lung myeloperoxidase (MPO) contents and morphological changes were evaluated.RESULTS: Gut ischemia/reperfusion induced rapid increase of serum IL-18 levels, peaked at 1 h after reperfusion and then declined. The levels of IL-18 in lung tissue were gradually enhanced as the progress of reperfusion.Compared with I/R group, exogenous administration of IL-18 (I/R+IL-18) further remarkably enhanced the pulmonary MPO activity and inflammatory cell infiltration,and in I/R+IL-18Ab group, the content of MPO were significantly reduced and lung inflammation was also decreased.CONCLUSION: Gut ischemia/reperfusion induces the increase of IL-18 expression, which may make IL-18 act as an important proinflammatory cytokine and contribute to gut ischemia/reperfusion-induced lung inflammation.

EFFECT OF PREOPERATIVE GLUTAMINE ADMINISTRATION ON ICAM-1 EXPRESSION IN RAT LUNG INDUCED BY INTESTINAL ISCHEMIA-REPERFUSION

Objective To evaluate the effect of preoperative glutamine administration on intracellular adhesion molecule-1 （1CAM-l） expression in rat lung induced by intestinal ischemia-reperfusion（ I/R）. Methods Sprague-Dawley rats （n = 25） were randomly divided into 5 groups： sham group （sham surgery）, glutamine groups （three different doses） and control group. All groups except sham were subjected to intestinal 1/R injury, and superior mesenteric artery （SMA） occluded for 60 min followed by 90 min of reperfusion. Lung injury was evaluated with Evans blue dye concentration and histopathologic examination. The immunohistochemical expression and mRNA expression of 1CAM-1 were measured with immunohistochemical staining and RT-PCR method respectively. The level of myeloperoxidase （MPO） was also measured with biochemistry method. Results Intestinal 1/R resulted in lung injury characterized by an increase in Evans blue dye concentration, neutrophil sequestration, and obvious staining for expression of pulmonary 1CAM-l, compared with sham group. The expression of 1CAM-1 and the level of MPO in rat lung were lower in glutamine groups compared with control group. Conclusion 1-R injury increases the expression of 1CAM-1 within the lung. This may contribute to the migration, accumulation and activation of polymorphonuclear neutrophils （PAINs） after such injury. Preoperative glutamine administration attenuates rat lung injury induced by intestinal I-R, and inhibiting 1CAM-1 expression maybe one of the potential mechanisms.

Effects of cardiopulmonary bypass on endothelial cell injury

Objective: To observe the changes of plasma concentrations of endotoxin, soluble intercellular adhesion molecule 1, tumor necrosis factor α, and urinary microalbumin in children undergoing cardiac procedure and to study the effects of cardiopulmonary bypass (CPB) on the injury or activation of endothelial cells and vascular permeability. Methods: Twenty children undergoing cardiac operation with CPB were selected in the study. Plasma concentrations of endotoxin, soluble intercellular adhesion molecule 1, tumor necrosis factor α, and urinary microalbumin were measured after anesthetic induction (baseline), bypass for 20 minutes, at the end of CPB, and at 2, 4, and 18 h after the end of CPB. Results: The plasma concentrations of endotoxin, soluble intercellular adhesion molecule 1, and urinary microalbumin began to increase at 2 h after the end of CPB, and remained higher than that of the baseline, while the concentration of tumor necrosis factor α increased only at the end CPB and at 2 h after the end of CPB. Conclusion: Cardiopulmonary bypass can induce inflammatory response, resulting in the activation or injury of vascular endothelial cells, and can increase the vascular permeability.

α_1-ANTITRYPSIN ATTENUATES ENDOTOXIN-INDUCED ACUTE LUNG INJURY IN RABBITS

Objective To investigate whether pretreatment with α 1-AT can attenuate acute lung injury (ALI) in rabbits induced with endotoxin. Methods Thirty-two New Zealand rabbits were randomly assigned to four groups(n=8):1.Infusion of endotoxin(Lipopolysaccharide,LPS 500μg/kg)without α 1-AT (group LPS).2.Infusion α 1-AT 120mg/kg at 15min before challenge with LPS(group LAV).3.Infusion of α 1-AT 120mg/kg(group AAT).4 Infusion of saline 4ml/kg as control (group NS).Arterial blood gases,peripheral leukocyte counts and airway pressure were recorded every 1h.Physiologic intrapulmonary shunting (Qs/Qt) was measured every 4h.After 8h the bloods were collected for measurement of plasma concentration and activity of α 1-AT.Then bronchoalveolar lavage fluid (BALF)was collected for measurement of concentrations of total protein (TP),interleukin-8(IL-8),tumor necrosis factor(TNF-α),the activities of elastase-like and α 1-AT,total phospholipids(TPL) and disaturated phosphatidylcholine (DSPC).In addition,the wet-to-dry lung weight ratio(W/D) was measured. Results After infusion of endotoxin,it was observed that PaO 2,peripheral luekocyte counts,total respiratory compliance progressively decreased and P peak and Qs/Qt increased comparing with the baseline values.In contrast to group NS,the increased plasma concentration but reduced activity of α 1-AT was found in group LPS.In the BALF,the activity of α 1-AT,TPL,DSPC/TPL were lower,but the concentrations of albumin,IL-8,TNF-α,and the activity of NE were higher.The ratio of W/D also increased.The pretreatment of α 1-AT attenuated the deterioration of oxygenation,the reduction of compliance and the deterioration of other physiological,biochemical parameters mentioned above. Conclusion Pretreatment with α 1-AT could attenuate endotoxin-induced lung injury in rabbits.Those beneficial effects of α 1-AT might be due in part to the inhibitory effect on neutrophil elastase.

Efficacy of continuous tracheal gas insufflation in spontaneously breathing canine with acute lung injury

Objective To investigate the effects of continuous tracheal gas insufflation (CTGI) combined with biphasic intermittent positive airway pressure (BIPAP) ventilation on dogs with spontaneous breathing. Methods Eight canine models with oleic acid induced lung injury and spontaneous breathing were ventilated in a random order by Evita 2 (Drager Inc., Germany) in modes of BIPAP (BIPAP group) and BIPAP with CTGI flow rate of 3, 6 and 9?L/min (T3, T6 and T9 groups), respectively. The setting parameters of BIPAP were fiction of inspired oxygen 60%, inspiratory to expiratory ratio 1∶1, respiratory rate 20 and positive end expiratory pressure 5?cm?H2O. Arterial and mixed venous blood gas, lung mechanics, systemic and pulmonary hemodynamics status were monitored at the same level of PaCO2 obtained by adjusting peak inspiratory pressure of BIPAP. Results Peak inspiratory pressure in the T6 group (14±4?cm?H2O) and in the T9 group (11±3?cm?H2O) were significantly lower than that of BIPAP (20±5?cm?H2O, P<0.01), but there was no significant difference among the T3, T6 and T9 groups or between the T3 and BIPAP groups. PaO2, mean artery blood pressure, mean pulmonary artery pressure, pulmonary artery wedge pressure, cardiac ouput, oxygen delivery and oxygen consumption all remained unchanged in four different conditions.Conclusions Using BIPAP combined with CTGI does not cause asynchrony between ventilator and spontaneous breathing, but significantly decreases airway pressure with no influence on hemodynamics and oxygenation. Therefore, BIPAP with CTGI may be a useful support technique, especially in cases where the airway pressure should be limited.

Effect of Radix Paeoniae Rubra on the expression of HO-1 and iNOS in rats with endotoxin-induced acute lung injury

Objective ： To investigate the effect of Radix Paeoniae Rubra （RPR） on the expression of heme oxygenase （ HO- 1 ） and induced nitric oxide synthase （ iNOS ） in endotoxin- induced acute lung injury in rats and its protective mechanism. Methods： Forty Wistar rats were divided randomly into 5 groups with 8 rats in each group： saline control group （NS group ）, lipopolysaccharide group （LPS group）, RPR-treatment group, RPR-prevention group and Hemin group. The effect of RPR on protein content, the ratio of neutrophiles in bronchoalveolar lavage fluid, malondialdehyde （MDA） content in the lung and the activity of serum NO were observed. Arterial blood was drawn for blood-gas analysis. The expression of HO-1 and iNOS in lung tissues was detected by immunohistochemitry and morphometry computer image analysis. The histological changes of the lung were observed under fight microscope. Results： Compared with that in NS group, the expression of HO-1 and iNOS was markedly increased in LPS group （P 〈0.01）. In RPR-treatment, RPR-prevention, and Hemin groups, the expression of iNOS was significantly lower, while the expression of HO-1 was higher than that in LPS group （P〈0.05）. The protein content, the ratio of neutrophiles in bronchouiveolar lavage fluid, the content of MDA and the activity of serum NO in LPS group were significantly higher than those in NS group （ P〈0.01 ）. There was a significant decrease in the level of arterial bicarbonate and partial pressure of oxygen in the LPS group （P 〈0.01）; these parameters of lung injury however, were significantly lower in RPR-treatment, RPR- prevention, and Heroin groups than LPS group （P〈0.05 or P〈0.01 ）. The pathologic changes of lung tissues were substantially attenuated in RPR-treatment, RPR- prevention, and Hemin groups than LPS group. Conclusions ： The high expression of HO-1 reflects an important protective function of the body during lipopolysaccharide-induced acute lung injury. The acute lung injury is related to the inhibition of iNOS expression and the induction of HO-1 expression.

Changes in pulmonary vascular endothelial cells after acute lung injury induced by bone marrow extract injection in rabbits

Objective: To investigate the changes of the markers of pulmonary vascular endothelial cells (PVECs) after acute lung injury (ALI) induced by bone marrow extract (BME) injection in rabbits. Methods: Thirty one rabbits were randomized into control (CG, n=10) and experimental groups (EG, n=21). The rabbits in EG were injected with homogeneous bone marrow extract (0.35 ml/kg, 2 ml/h) at a slow and continuous rate through the jugular vein to establish the model of ALI. At 6 h after the injection, the number of circulating endothelial cells (CECs) in the blood, contents of granule membrane protein 140 (GMP 140), angiotensin converting enzyme (ACE) and endothelin 1 (ET 1) in the plasma and the content of GMP 140 in the pulmonary tissue were determined at various time intervals. Then the animals were killed and routine pathological examination and electron microscopy were performed to observe the changes in the pulmonary tissue. Results: The levels of plasma GMP 140, ACE, ET 1 and CECs were significantly increased in the early stage ( 0.5 h) and remained higher for 6 h. The marked increase of plasma GMP 140 (3.25 times) in the early stage was negatively correlated to PaO 2, but positively to other parameters. IHC staining showed that the GMP 140 on the surface of PVECs became weak. Conclusions: BME injection at slow and continuous rate can establish an acceptable model of ALI. Determination of plasma GMP 140 might be an important measure for the early surveillance and the evaluation of prognosis of ALI in clinical management of serious traffic accidents.