| Objective: Observe the effect of Annexin A1 peptide Ac2-26 on the systemic inflammatory response and lung injury after cardiopulmonary bypass in rats to explore its protective effect on lung and anti-inflammatory mechanism after cardiopulmonary bypass.Methods: Eighteen SPF male SD rats were selected,weighing 350~450g,and divided into 3 groups according to random number method(n=6).Sham operation group was s group,left lung ischemia-reperfusion injury group was IR group,ac2-26 group was a group.All rats in each group were fixed in supine position after anesthesia,catheterized by tail vein,left and right femoral vein,right femoral artery and common carotid artery,intubated by laryngoscope,connected with ventilator for mechanical ventilation,and finally connected with the right femoral artery and biological signal acquisition system.In group s,the rats were punctured outside the chest without any other treatment.The left lung ischemia-reperfusion injury model was established in the other two groups of rats.The right common carotid artery was connected with peristaltic pump,and the femoral vein was connected with rat membrane oxygenator.The rats in group A were given exogenous ac2-26 10 minutes before blocking the hilus,while those in group IR were given the same volume of normal saline 10 minutes before blocking the hilus.In IR group and a group,before CPB(T1),immediately after opening left pulmonary hilum(T2)and at the end of the experiment(T3),the femoral artery blood was taken from Group s at the corresponding time point,and the action pulse blood gas was analyzed and the oxygenation index(OI)and respiratory index(RI)were calculated.At the same time,the vital signs of the rats were recorded.At the time of T1 and T3,the number of neutrophils in femoral vein blood was measured;at the time of T3,the number of neutrophils and the content of VCAM-1 in pulmonary artery blood were measured;at the end of the experiment,the left lung tissue was taken and divided into four parts,which were fixed in formaldehyde and glutaraldehyde solution and stored in-80 ? refrigerator.Morphological changes of lung tissue were observed under light microscope;NE and MPO contents of lung tissue weremeasured by ELISA;neutrophil apoptosis was measured by TUNEL method;expression of ANXA1 and ICAM-1 in lung tissue was detected by Western blot.Results:(1)Changes of lung function in each group Comparison of OI(oxygenation index)and RI(respiratory index)at different time points in each group: there was no significant difference between OI and RI in s group at each time point(P > 0.05);compared with T1 time point,OI and RI in T2 and T3 time points in each group were significantly lower and higher(P < 0.05).Compared with T2 time point,IR and oi of group a decreased and RI increased significantly at T3 time point(P < 0.05).At the same time point(oxygenation index)OI,(respiratory index)RI,there was no significant difference(P > 0.05).At T2 time point,compared with s group,OI in IR and a group was significantly lower and RI was significantly higher(P < 0.05),but OI in a group was not significantly different from that in IR group(P > 0.05).At T3,OI in IR and a group was significantly lower than that in s group and RI was significantly higher than that in s group(P < 0.05);OI in a group was significantly higher than that in IR group and RI was significantly lower than that in IR group(P < 0.05).(2)At the end of the experiment,the results of light microscopy and the scores of pathological damage of lung tissue in each group Under the optical microscope,In group S,the lung tissue structure was clear,and the alveolar wall was complete;in group IR,the lung tissue structure was disordered,the alveolar wall was broken,and the alveolar cavity was filled with edema fluid,with moderate amount of inflammatory cells and red blood cells infiltration,and the degree of lung injury was more serious than that in group S;in group A,the lung tissue structure was relatively complete,only part of the alveolar wall was broken,with a small amount of inflammatory cells infiltration,and the degree of lung injury was significantly lighter than that in group IR.The scores of lung injury in group A and IR were significantly higher than those in group S(P < 0.05).The lung injury score of group A was significantly lower than that of group IR(P < 0.05).(3)Comparison of PMN in femoral vein blood at T1 and T3 in each group of rats At different time points in each group: there was no significant difference in the number of PMN in femoral vein blood at T1 and T3 time points in group S(P > 0.05);the number of PMN at T3 time points in group IR and group A was significantly higher than that at T1 time points.There was no significant difference in the number of PMN in femoral vein between the three groups(P > 0.05).At T3 time point,compared with S group,the number of PMN in IR group increased significantly(P < 0.05),while that in a group decreased significantly(P > 0.05).(4)Comparison of PMN quantity in pulmonary arterial blood of rats in each group at the end of the experiment Compared with the S group,the number of PMNs in the pulmonary veins of the rats in the IR and A groups was increased(P <0.05);the number of PMNs in the pulmonary veins of the rats in the A group was lower than that in the IR group(P <0.05).(5)At the end of the experiment,VCAM-1 content in pulmonary artery blood of each group was compared Compared with group s,the content of VCAM-1 in pulmonary artery blood of rats in group IR and group a increased(P < 0.05);the content of VCAM-1 in pulmonary artery blood of rats in group A was lower than that in group IR(P < 0.05).(6)At the end of the experiment,the content of NE and MPO in lung tissue of each group was changed Compared with group s,the content of NE and MPO in lung tissue of group IR and group A increased significantly(P < 0.05);the content of NE and MPO in lung tissue of group A decreased significantly lower than those in the IR group(P < 0.05).(7)The end of the experiment in each group of rats is the neutrophil apoptosis in lung tissue At the end of the experiment,there were no obvious apoptotic cells in group S,and the neutrophil apoptosis rate in group A was significantly higher than that in IR group(P<0.05).(8)Expression of ICAM-1 and AnxA1(37KD)in lung tissue of rats in each group at theend of the experiment Compared with the S group,the expression of ICAM-1 in the lung tissue of the rats in the IR and A groups was increased(P <0.05);compared with the IR group,the expression of ICAM-1 in the lung tissue of the rats in the A group was reduced(P <0.05).Compared with the S group,the expression of AnxA1(37kD)in the lung tissue of the IR and A groups increased(P <0.05);compared with the IR group,the expression of AnxA1(37kD)in the A group decreased(P <0.05).Conclusion:(1)CPB can reduce lung function,destroy lung structure and delay PMN apoptosis in rats,causing damage to rat lung tissue.(2)Ac2-26 can inhibit systemic inflammatory response,improve lung function after CPB in rats,reduce the degree of lung injury,and have a certain lung protective effect on CPB rats.(3)The mechanism of Ac2-26 reducing CPB lung injury in rats may be related to regulating the expression of AnxA1(37kD)in lung tissue,reducing PMN adhesion to pulmonary vascular endothelium,promoting PMN apoptosis in lung tissue,and reducing NE and MPO content. |
PDF Full Text Request