Role of apoptosis in the pathology of pneumonic pasteurellosis in naturally infected pigs

Abstract

Pneumonic Pasteurellosis caused by Pastenrella mnltoeida is an economically important veterinary pathogen confronting swine industry worldwide. Despite continuous investigations on its various aspects of pathogenesis, role of apoptosis and its pathway in the development of lesions has not been investigated. Thus, the authors investigated the role of various apoptosis pathways in the pathogenesis of lesions in pigs suffering pneumonic Pasteurellosis. A total of 10 lungs tissues from pigs naturally died of Pasteurellosis were subjected to immunohistochemical investigation for the demonstration of apoptosis and its pathway. Caspase-3 & Annexin-V staining were markedly stronger in the inflammatory cells and the endothelial lining cells of the blood vessels confirming the role of apoptosis. The caspase-8 staining was more pronounced in the inflammatory cells adjacent to necrotic lesions throughout the sections of the lungs whereas mild to moderate immunoreactivity of Cacaspase-9 was noticed only in focal areas of 2 cases. In addition to it, moderate P53 staining was noticed surrounding the necrotic lesions. However, the tissues failed to show any immunolabelling for Apafl and Bcl-2 antibodies. This study clearly illustrates ex vivo that the activation of the P53 mediated caspase dependent extrinsic pathway is a key element in the pathogenesis of pneumonic lesions observed in pigs infected with Pastenrella mnltoeida.