Pathologic Dynamics Observation On Lung Injury Of Duck Infected With Pasteurella Multocida And The Expression Of Pulmonary Edema Associated Genes

Pasteurella multocida is a worldwide epidemic pathogen that can widely cause a variety of human and animal disease. Pasteurellosis of ducks is also called fowl cholera or duck hemorrhagic septicaemia, which is urgent, infectious and has a high mortality. The disease characterized by dyspnea, shaking heads frequently or whirling, diarrhea. In most cases, lung lesions occur consistently. The typical anatomical changes of lung include pneumorrhagia and pulmonary congestion and edema.Pulmonary edema can be caused by the damage of alveolar epithelial barrier and increased alveolar capillary permeability. And angiotensin II, the main effector molecule of renin-angiotensin system(RAS), is thought to induce those damages and activate MAPK or NF-κB signaling pathway to mediate the inflammation. Also, previous research has shown that AQP1(Aquaporin 1) and AQP5(Aquaporin 5) have a closely relate to pulmonary edema.To understand the mechanism of pulmonary edema caused by Pasteurella multocida, In this work, 30-day-old ducks were experimentally inoculated P.multocida to study the pathological changes of lung, detect the expression changes AQP1, AQP5, AT1 R and TNF-α mRNA through histologic technology and real-time fluorescent quantitative PCR. Finally, the relationships among pathological changes and those indexes would be evaluated. It turned out that: 1. Pasteurella multocida could cause significant pathological changes of lung such as edema, congestion and bleeding.Broadening of interlobular septa, serous effusion in parabronchus and lung interstitial,severe hemorrhage of air capillary and atrium and infiltrate of inflammatory cells were observed. 2. AT1 R mRNA expression increased in lung at 4h-36 h of post infection and decreased at 48 h of post infection. There was no significant difference compared with control group(P>0.05); AQP1 m RNA expression decreased at 4h-48 h of post infection.There was no significant difference compared with control group(P>0.05); AQP5 mRNA expression decreased at 4h, 12 h, 36 h, 48 h and increase at 24 h of post infection. There was no significant difference compared with control group(P>0.05); TNF-α mRNA expression increased at 4h-36 h of post infection and decreased at 48 h. There was nosignificant difference compared with control group(P>0.05).This work had clarified for the first time that there were expression of AQP1, AQP5 and AT1R in duck lung which meant local renin-angiotensin system(RAS) did existed in duck lung. Combined with histologic changes indicated that the lung air-blood barrier was damaged so that the fluid balance was destroyed which led to edema and congestion.Combined with the decreased mRNA expression of AQP1, AQP5 and the increased mRNA expression of AT1 R, TNF-α, there was a reason to believe it had a correlation among AQP1, AQP5, AT1 R and pulmonary edema of duck.