The Study On The Location And Expression Of Proteinase-actived Receptor-2in The Respiratory Tract Of Pigs Infected With Haemophilus Parasuis

The Haemophilus parasuis disease,caused by Haemophilus parasuis is a kind of respiratory disease which is characterized by cough,limp,difficulty in breathing and disorder fur. With the expansion of pig industry, The Haemophilus parasuis disease has been posing a more serious threat to the industry. The protease-activated receptor-2(PAR-2) is a member of the G-protein-coupled receptor family. family. Studies have shown that PAR-2has a wide tissue expression especially tissues which are likely to occur allergy such as the gastrointestinal tract and the respiratory tract. The PAR-2will stimulate the cells to secrete a variety of inflammatory mediators and cytokines when it is activated. These reactions play a role of regulation in many physiological and pathophysiological processes.Recent researches on PAR-2are mostly focused on the disease models of humans and mice. There are not many researches on pigs, especially naturally infected ones. Pigs suspected to be infected with Haemophilus parasuis are selected in this study. Respiratory tissues are collected, and then Gram’s stain and PCR are used for the identification of the bacteria. The pathogen is conformed to be Haemophilus parasuis. The histopathological changes of respiratory tracts were examined by HE staining. The location and expression of PAR-2protein in the different tissues was measured by IHC and Real-time PCR. It is designed to discuss the distribution, expression and significance of PAR-2.The results analysis shows that:(1)The pathogen is Haemophilus parasuis.(2) The hematoxylin-eosin staining showed desquamation and denaturation in the epithelium mucosae,the airway integrity is damaged. There are more inflammatory cells and some red blood cells in the airway lamina propria.At the same time,a lot of neutrophils,fibroblasts and some serous effusions are in the alveolar.(3) Immunohistochemical analyses clearly showed abundant expression of PAR-2in the respiratory tracts of the sick pigs, especially in the apical region of epithelium mucosae and basilar part of gland cell.In addition,the PAR-2was found in the neutrophils and fibroblasts. But no positive reaction of the PAR-2was found in the control group. At the level of gene expression, both tissues of tracheas and lungs of the sick pigs showed a higher expression of PAR-2compared with the normal control group. In Conclution, this study demonstrates wide expression of PAR-2in the respiratory tracts.During the time when pigs infected by Haemophilus parasuis (or some other respiratory diseases),the expression of PAR-2in the respiratory tract will have a significant increase.We hypothesize that the expresstion level depends on the inflammation state or the disease progression. More researches are to be carried out to get the details of the regulatory pathways.