Analysis of histopathology and changes of major cytokines in the lesions caused by Mycoplasma ovipneumoniae infection

Abstract

Abstract Background Mycoplasma ovipneumoniae (M. ovipneumoniae) is wide epidemic in the world, and is the main pathogen of sheep pneumonia, causing a series of clinical symptoms, such as depression, anorexia, hyperthermia, cough, dyspnea and tract secretions and so on. In recent years, the prevalence of M. ovipneumoniae pneumonia has become increasingly serious in sheep farms in Ningxia, China, causing significant losses. Results In this study, a total of 105 samples were collected from 13 large-scale farms in Ningxia for pathogen isolation, identification, pathological dissection and histopathological observation. The results showed that 13 strains of M. ovipneumoniae were isolated from the samples collected from 13 farms. The lesions caused by M. ovipneumoniae were mainly in trachea, bronchus and lung, including necrosis of tracheal mucosal epithelial cells, disintegration of some epithelial cells, edema of mucosal lamina propria, with inflammatory cell infiltration, cytoplasmic vacuolization of epithelial cells of bronchial mucosa, massive infiltration of inflammatory cells in the alveolar space of lung, necrosis and hyperplasia of alveolar epithelial cells. Immunohistochemical analysis showed that the proportion of M. ovipneumoniae positive area in lung was the largest, followed by that in bronchus and trachea. The mRNA expression of cytokines in target organs were detected by qPCR. The results showed that the cytokines of significantly up-regulated mRNA expression in trachea was IL-12. The cytokines of significantly up-regulated mRNA expression in the bronchus included IL-10 and IL-12. The cytokines of significantly up-regulated mRNA expression in the lung included IL-1β and NF-κB. Conclusions Molecular identification of pathogens, immunohistochemical analysis and detection of inflammatory cytokines of lesion tissues play important roles in the diagnosis of M. ovipneumoniae infection. This study lays a foundation for the diagnosis, prevention, control and pathological damage mechanism of M. ovipneumoniae pneumonia.