Study On IL-17-Induced Lung Pathological Damage In The Progression Of CPPP

Contagious caprine pleuropneumoniae(CCPP)is a highly contagious fibrinous pneumonia with its the incidence of 22%~30%,some up to 60%~80%,the mortality rate of 15%~30%,caused by Capricolum subsp.capripneumoniae(Mccp),which poses a great threat to the world’s goat-raising areas.At present,the study of the CCPP mainly focuses on the separation and identification of pathogens and epidemiological investigation,but the mechanism of immune pathogenesis in the progression of CCPP was reported rarely.In this study,the nasal swabs from the suspected goat with CCPP were collected and diagnosed subsequently by PCR.following isolation and culture of pathogens,identification of molecular biology methods,animal regression experiment.The CCPP model was established on goats by inoculation the Mccp strain intratracheally.to explore the changes of IL-17 and its related cytokines and immune cells in PBMCs and lungs.Whole protein of Mccp was used to stimulate PBMCs as well as primary lung derived cells in vitro,in which IL-17 and its related cytokines at mRNA level were measured by real-time PCR.Goat lung epithelial cells were stimulated by rIL-17 protein to explore the changes of chemokines at mRNA level.The primary results of this study as following:1.The separated and purified strain under light microscope showed a central umbilical cord with a smooth edge,fried egg-like.Biochemical tests were consistent with the characteristics of Mccp.Sequence analysis indicated that the isolate was shared 99.8% with the Mccp in Genbank.2.Goats infected Mccp showed the typical clinical symptoms and pathological changes of CCPP.The PCR of lungs homogenization was tested with Mccp positive and the Mccp pathogen was isolated in the lungs.3.In CCPP model,the number of neutrophils in blood and lung tissue increased significantly and the proportion improved(P<0.05).The content of NO in serum,plasma and lung tissue increased and the activity of T-SOD in plasma and lung tissue decreased,and the content of MDA increased(P<0.05).IL-17 and its associated cytokines in PBMCs and lung tissues were increased significantly(P<0.05),4.The mRNA level of IL-17 was increased significantly and IL-23p19,TNF-α,IL-1β,IL-12 expression were improved as well as the chemokine IL-8,CCL20,CCR6 in PBMCs stimulated by whole protein of Mccp.5.Primary lung derived cells were stimulated by whole protein of Mccp with the transcription level IL-17 increasing significantly and the TNF-α,IL-1β,IL-12,IL-6,TGF-β expression were improved as well as the chemokine IL-8.6.rIL-17 protein induced the expression of chemokine IL-8、CXCL1、CXCL6、CCL20,CCL4 increasing significantly at mRNA level in lung epithelial cells(P<0.05).In conclusion1.Isolation and identification of one strain of Mccp with strong pathogenicity,named M599.2.The goat CCPP model was successfully established.3.The experiments in vitro and in vivo proved that IL-17 and its related cytokines,neutrophils chemokines and neutrophils mediated the immune pathological damage in CCPP of goat.