The Expression Of Tight Junction After LPS-induced Acute Lung Injury In Rats Lung

IntroductionALI was directly or indirectly caused by various kinds of exterior and interior etiological factor.ALI was acute progressing respiratory failure.Main pathological characteristic of ALI was diffuse impairment in the alveolar capillary membrane and hyperpermeability and pulmonary edema.At present,many scholar presume that the principal pathogenesy of ALI was hyperpermeability of alveolar capillary membrane. The endotoxin was directly or indirectly injure alveolar epithelium and vascular endothelial cell and therefore cause hyperpermeability of alveolar and endothelial cell. The pore size of the capillary of the lung was four times than that of the alveolar epithelium.So investigate the alveolar epithelium was more significant than the vascular endothelial cell.As the apical member of the junctional complex,the TJ forms a continuous,circumferential,belt like structure at the luminal end of the intercellular space,where it serves as a gatekeeper of the paracellular pathway.There were of importance TJ such as Zo-1 and Occludin.At present,there are no research regarded to ALI and TJ at domestic.We investigate that endotoxin can cause the change of the expression of Zo-1 and Occludin on the alveolar epithelium,and suppose the possible mechanism which ALI was associated with the expression of TJ.And provide the theoretical approach to treatment ALI.Material and MethodsExperimental Material1.Experimental Animal SD rat,male,weight 220-270g.2.Experimental DrugsLPS:E.coli,endotoxin 055:B5 LPS;Sigma.Co.anti-Occludin and anti-Zo-1 polyclonal antibodies were from Santa Cruz.U.S.A.All secondary antibodies were from peking zhong san golden bridge Biotechnology.3.Experimental equipmentElectrothermal constant temperature incubator:DNP-9262 model.Shanghai jinghong testing limited company.Microwave oven:WD-700 model.LG electron Tianjin appliance limited company.Microscope:CX-41RF model.Philippines. Microgram image analysis system:Meta Morph/DP 10/BX41,UIC/OLYMPUS,US/JP. Multichannel physiological signal collection processing system RM 6240 BD model. Chengdu equipment factory.Animal model experimental group and tissue preparationA total of 30 SD rats were randomly assigned to the control group(n=10),and the injured group(n=20)in which the lung injury was induced by intratracheal instillation of LPS at the dose of 0.5ml/kg.Rat were anesthetized with 10%chloral hydrate(300mg/kg)intraperitonealy.The carotid artery was cannulated for measurement of arterial blood pressure.Chest was opened and observed the morphous of the lung.Lung was first perfused by its main bronchus with NS and rinsed the lung tissue until the lung tissue became pure white. Left bronchus was ligated and lung tissue was removed and put it into box containing fixative solution 4%paraformaldehyde and immersed in the fixative for 24h and embedded in paraffin and made tissue wax block.Immunohistochemical staining were completed to detect the expression of Occludin andZo-1,remnant lung tissue were weighted for W/D.Statistical analyses.Results are presented as means±S.Data were analyzed using analysis of variance(F test)with SPSS13.0.P values of less than 0.05 considered significant.Resultspathological change of lung tissuesThe lung observed in the NS group was non apparent abnormality.After LPS administration,lung showed marked alveolar infiltration with inflammatory cells, effusion,red blood cell and interalveoiar septa was thickened especially in the LPS4h group.Lung W/D indicate that ALI4h rat(6.65±0.58)were significantly difference than normal control group(4.50±0.42)P＜0.05,however,ALI24 group(4.82±0.55)have no significant difference compared to the normal control group.This explain pulmonary edema was the most severe in the ALI4h group.The blood pressure of the rat was decreaed after LPS,ALI4h group(64±6.0)was significantly decreased than normal control group(96±5.0),however,ALI24 group(85±6.0)have no significant difference compared to the normal control group.Immunohistochemical stainingIn the normal control group(40.97±8.01)the expression of Occludin was a great quantity on the alveolar epithelial cell.In the LPS4h group(20.5±3.68)was lower than that of the normal control group(40.97±8.01)and compared to the normal group the value of the Occludin have significance difference P＜0.05.In the LPS24h group (32.77±3.40)was ameliorated but compared to the control group the value of Occludin still have significance difference p＜0.05.In the normal control group (48.63±5.15)the expression of Zo-1 was a great quantity on the alveolar epithelial cell.In the LPS4h group(20.77±5.08)was remarkably lower than that of the normal control group(40.97±8.01)and compared to the normal group the value of the Zo-1 have significance difference p＜0.05.In the LPS24h group(39.20±8.42)was ameliorated and compared to the control group the value of Zo-1 have no significance difference p＞0.05.ConclusionThe levels of Zo-1 and Occludin were decreased in the early stage of acute lung injury.The expression of Zo-1 and Occludin on the alveolar epithelial was associated with acute lung injury.