5-Lipoxygenase and cyclooxygenase-2 in the lungs of pigs naturally affected by enzootic and porcine pleuropneumonia

Eicosanoids are products of arachidonic acid metabolism and have numerous biological roles. The present study aimed to ivnestigate the fole of 5-lipoxygenase (5-LOX)- and cyclooxygenase-2 (COX-2)- dependent enzymatic pathways in the pathogenesis of porcine parasitic bronchopneumonia caused by Metastrongylus spp. Pulmonary tissue samples from healthy control and parasitized pigs were proessed for histophathological, immunohistochemical and bichemical investigations. In control animals, immunohistochemistry demonstrated that 5-LOX and COX-2 expression was almost exclusively limited to the bronchiolar epithelial cells. Paratsitized pigs had greated 5-LOX- and COX-2- specific immunoreactivity, involging a wide range or cell types within foci of granulamatous and eosinophilic bronchopneumonia. Biochemical investigations demonstrated the presence of 5-LOX (and the realted product Leukotriene B(4)) and COX-2 (and the related product prostaglandin E(2); PGE(2)) in all tissues under study. COX-2 activity and PGE(2) concentration were significantly higher in diseased lungs compared with normal healthy controls. These findings demonstrate that 5-LOX and COX-2 are differentially expressed in normal versus lungworm-infected lungs and therefore suggest that both biochemical pathways are likely to be involved in the pathogenesis of parcine parasitic bronchopneumonia