Study On Immunolocalization Of Proteinase-activated Receptor-2 In The Gastrointestinal Tract Of Piglets Infected With Salmonella Typhi

Background and Object: Diarrhea of weaning piglets are generic names of diarrhea diseases by many factors originated in weaning period of time of piglets, which influence growth and development, ability to resist disease and transformation efficiency in feedstuff. Protease activated receptor-2 (PAR-2) belongs to family of G-protein-coupled receptors for serine proteases. Distribution of PAR-2 is widely distribution in organism. PAR-2 activation can induce inflammatory mediators or cytokine secrected and play multiple physiological and pathophysiological roles. Study diversity rule in distribution and quantity of PAR-2 through normal piglets and diarrhea piglets, the relationship is correlated between function of PAR-2 and development of diarrhea in piglets.Methods: According to histology characteristics, weaning piglets' gastrointestinal tract were divided into gastric cardia, gastric fundus, pylorus, duodenum, jejunum, ileum, colon and appendix, et al. The tissues were fixed by PLL, embedded and sliced (4μm). Microbiology pathogenic bacterium were isolated and identified from the intestinal content. The tissue paraffin slides were stained by SABC with goat polyclonal antibody against human PAR-2, and observed the immunolocation of PAR-2 by optical microscope. And negative tissues were the healthy piglets' tissues with omission of primary antibody. At the same time, the results were contrasted between H. E. staining and SABC staining.Result indication:1. Diarrhea piglets were disseted and observed that part of tissue occured cheese pathological change. And plasma membrane had different level bleeding point all over the body. They were thinness about GI tract content. And there were much mucus on the surface of mucosa. Bowels wall were thickness and elasticity decreased. We found that the main pathogenic bacterium in the field was salmonella typhisuis trough culture and abstraction.2. Most pathological changes showed desquamation and denaturation in the epithelium mucosae, smooth muscle thinning of bowels, infiltrated neutrophil and eosinophil in the lamina propria with H. E. staining. And lymph nodules were hyperplasia in the submucosa. They showed different inflammation degree.3. Immunohistochemical analyses clearly showed abundant expression of PAR-2 in the GI tract of piglet, especially in the apical region of epithelium mucosae and basiiar part of gland cell, and was found in vascular endothelial cell, fibroblast, neutrophil, eosinophil, et al. But control group wsa found no positive reaction. Further, immunoreaction of PAR-2 was more expressed in the diarrhea pigs than in the normal ones, even in the inflammatory cell.In conclusion, this study demonstrates expression of PAR-2 widely in the GI tract, but which was lower in small intestine than in the gastro and large intestine. It is strongly immunolocalizated in the inflammatory cell during the early days of diseases. It is known that PAR-2 has dual effects between healthy and sickness. This may be contributed to treat various kinds of diseases by PAR-2-AP or PAR-2 agonist.